Anatta & Atman the same thing?

Is it possible that these deep concepts are pointing to the same thing at the end of the day?

Yes I think so.

Part of Buddhist doctrine is, more-less, that self-views are a cause of suffering.

I get the (not very well-informed) impression that the Hindu tradition includes teaching something like, neti neti -- "the self is not this".

A corollary of that search might be that the "self" or Self is something other -- is Atman or Brahman.

Perhaps a Hindu would expect a Buddhist to somehow identify with Nibbana (or the Tathagata), see that as some refuge for a sense of self (or of being, or of action, etc.).

So if selfishness and identifying with the body and the shandhas is an extreme (worldly) position, maybe Atman and so on is logically opposed to that -- and a different extreme!

Whereas Buddhism being a middle way, neither extreme, might say, "not the other extreme either -- i.e. also nibbana isn't self, is anatta".

Wikipedia's Paramatman suggests that the (or some) Hindu doctrine might be similar somehow ...

Selflessness is the attribute of Paramatman, where all personality/individuality vanishes.

... but that article's comparison with Buddhist doctrine says only ...

Buddhism rejects a metaphysics of "ground" such as the paramatman.

I think that there is some Buddhist "metaphysics", and sometimes some doctrine about "ground" (but those are a couple of words I don't know enough of at the moment to explain).

It is vey possible that anatta and atman are the same thing.

In Buddhism, Anatta means "non-self." However if the self doesn't exist, what travels from birth-to-birth? According to Lord Buddha the "stream of consciousness" which is essentially karmic energy, travels to different life forms.

In Hinduism the Atman is energy. It is considered the soul. The "karmic energy" in Buddhism is identical to the concept of energy as the Atman.

The difference is that Hindus attribute Atman to the self, whereas Buddhists say that the stream of consciousness is everchanging because of the 5 aggregates therefore it cannot be attributed to the self. So Buddhists do not cling to the stream of consciousness because of this.

Atman

Atman is the only refuge (DN 2. 100). The uncreated. (“The soul” Ive heard as one translation several times)

Anatta

Anatta is a method (Labeling as ‘not self’), and a characteristic of this reality (it is all empty of any selfhood).

Atman is attained by seeing* that all of phenomenal reality is Anatta (empty of agency and selfhood, conditioned and caused, impersonal)

Realizing the true Atman (soul imo) can be helped by noting ‘This is not self’ about everything ever perceived or conceived or imagined (which is the practice of Anatta).

Summary

So yes, they are highly related.

*Note And by seeing that phenomenal reality is anicca and dukkha too. Anicca meaning ever changeful, and dukkha meaning cannot satisfy, will cause suffering if clung to.

In the Suttas:

Buddha said Atman is the only refuge (DN 2. 100).

Buddha taught centrally that we reincarnate

Buddha said the Atman is the “charioteer of the person”

Buddha said because there is the transcendent Unconditioned, there is hope in the conditioned.

“The eightfold path is the best of paths

For it leads safely to the Deathless."

-- MN 75:

————

Buddha said that in all of conditioned, phenomenal existence, there is anatta (no selfhood); no permanence; and no satisfaction. We must let go and attain the transcendent unconditioned Atman

https://youtu.be/FEnb2cFWKBs

Atman is 'self', Annata is 'no self'. It's apparent that they are complete opposites. But could they be the same? Ask a classical Zen master and you might get a good bonk on the head with his staff. Which is another way of saying, that's a pretty good question! You can try to answer, but why spoil it? Maybe the best questions should be left unanswered. Just keep asking the question... The Hindu "I am that" and the Buddhist "I am not that" The same?

What is atman? If you refer to atman as a soul which transmigrates after death then you are wrong. There is no soul which transmigrates after death. Rebirth is just an echo of what was the last consciousness at the time of death. Rebirth is like a stanza learned by student from a teacher.

If you refer to atman which is the listener of the ears, seer of the eyes, smeller of the nose, comprehender of the mind then again I am afraid Buddha says there is no such atman.

Buddha goes on to say there is no Atman... Atman is like a illusion. In other words there is no self worth identifying as my or your soul. Like all illusions, the illusion of atman must collapse. Once that happens gates of Nirvana opens for you. As you see the concept of Atman and Anatta are opposite of each other.

Hindus live in the world of Brahman... Understanding of Brahman is the ultimate goal. Buddhists do not live in any such world. Therefore I am afraid Buddhist philosophy leads to a different state of mind. Should we describe that state as blissful ? That I can not answer for sure but it seems blissful is the right answer. Is that blissfulness permanent ? Yes in both the cases it is said to be so. Is that blissfulness me ? Hindus says Yes that blessedness is your self. Buddhists say there is no self.

Hinduism's Atman is the imperishable and indestructible immortal soul or self that pervades the entire body.

That which pervades the entire body, know it to be indestructible. No one can cause the destruction of the imperishable soul. Only the material body is perishable; the embodied soul within is indestructible, immeasurable, and eternal. ... Neither of them is in knowledge—the one who thinks the soul can slay and the one who thinks the soul can be slain. For truly, the soul neither kills nor can it be killed. The soul is neither born, nor does it ever die; nor having once existed, does it ever cease to be. The soul is without birth, eternal, immortal, and ageless. It is not destroyed when the body is destroyed.

Hindu text Bhagavad Gita 2.17-20

Buddhism's Anatta is from the statement "sabbe dhamma anatta" (Dhp 279) which means that "all phenomena is not self".

So, Atman and Anatta are opposite.

Then the Venerable Ānanda approached the Blessed One … and said to him: “Venerable sir, it is said, ‘Empty is the world, empty is the world.’ In what way, venerable sir, is it said, ‘Empty is the world’?”

“It is, Ānanda, because it is empty of self and of what belongs to self that it is said, ‘Empty is the world.’ And what is empty of self and of what belongs to self? The eye, Ānanda, is empty of self and of what belongs to self. Forms are empty of self and of what belongs to self. Eye-consciousness is empty of self and of what belongs to self. Eye-contact is empty of self and of what belongs to self…. Whatever feeling arises with mind-contact as condition—whether pleasant or painful or neither-painful-nor-pleasant—that too is empty of self and of what belongs to self.

“It is, Ānanda, because it is empty of self and of what belongs to self that it is said, ‘Empty is the world.’”
SN 35.85

According to the Hindu school of Advaita Vedanta, Atman is Consciousness:

Atman is all consciousness and holy, the body is all flesh and impure; and yet, etc., - verse 19

Thus all the three states are unreal inasmuch as they are the creation of the three Gunas; but their witness (the reality behind them) is, beyond all Gunas, eternal, one, and is Consciousness itself. - verse 58

The wise should always think with great care of the invisible, the visible, and everything else, as his own Self which is consciousness itself. - verse 141

Adi Shankaracharya's Aparokshanubhuti

According to the Buddha, Consciousness is dependently originated and is impermanent. It's not the same Consciousness that roams throughout one's life and continues to another life:

The Buddha said to him, “Is it really true, Sāti, that you have such a harmful misconception: ‘As I understand the Buddha’s teachings, it is this very same consciousness that roams and transmigrates, not another’?”

Sati: “Absolutely, sir. As I understand the Buddha’s teachings, it is this very same consciousness that roams and transmigrates, not another.”

Buddha: “Sāti, what is that consciousness?”

Sati: “Sir, it is he who speaks and feels and experiences the results of good and bad deeds in all the different realms.”

Buddha: “Silly man, who on earth have you ever known me to teach in that way? Haven’t I said in many ways that consciousness is dependently originated, since consciousness does not arise without a cause? But still you misrepresent me by your wrong grasp, harm yourself, and make much bad karma. This will be for your lasting harm and suffering.”
MN 38

The same sutta explains that consciousness arises dependent on the six sense media and their sense objects.

The two are opposites. One is Pali (anatta) and the other is Sanskrit (atman).

Anatta translates to the Sanskrit as anatman, often translated into English as 'no-self', or 'no-soul', and represents the teachings against there being an ontological or surviving soul (atman) as taught by many religions. The 'an' portion indicates 'no', which indicates why the two are opposite in meaning.

I have never read 'anatta' is 'pure bliss'. 'Bliss' is a feeling where as 'anatta' is a characteristic of things that is realised by wisdom.

As for 'Atman', this appears to be a concept that changed & evolved throughout the history of Brahmanism & Hinduism. At the time of the Buddha, it appears 'Atman' did not mean bliss or a transcendent state.

The earliest use of word "Ātman" in Indian texts is found in the Rig Veda (RV X.97.11). Yāska, the ancient Indian grammarian, commenting on this Rigvedic verse, accepts the following meanings of Ātman: the pervading principle, the organism in which other elements are united and the ultimate sentient principle.

This is probably why the word 'anatta' does not mean 'not-bliss'.