What is the root condition for (each of the) unwholesome roots of greed, ill-will and delusion (raga, dosa, moha)?

It's because not seeing, not knowing, Dukkha, e.g. lack of recognising Dukkha, that the roots of Dukkha arise. Is because not hearing/remembering the good Dhamma with proper attention, that lobha, dosa and moha penetrates the mind. And what is the lack of Dukkha, as a cause of Saddhā/Saddha (sacrifice) arising? Birth is the cause of Dukkha. So it's by taking birth, by coming into being at auspicious conditions and hearing/remembering the Dhamma at proper time, that path and fruit, the way beyond is obtained, conditions for further becoming uprooted, abound.

[Note: this is a gift of Dhamma, not thought for trade, stakes, exchanges or other gains subject toward decay and should be deleted if it's not giften to give in Dhammic conditions]

Because we chase delight, relishing and craving, there is suffering. Thinking to have only delight, we run away from pain, chasing pleasure. This is delusion.

Nandī dukkhassa mūlan’ti. Delight is the root of suffering --MN1/Bodhi

We build our identities on this chase, running after pleasure, avoiding pain, building up our selves, refusing to see the wisdom of the Four Noble Truths:

The noble truths of suffering, the origin of suffering, the cessation of suffering and the way of practice that leads to the cessation of suffering --MN141/Sujato

The way out is the Noble Eightfold Path. Start with Right View:

A noble disciple understands the unskillful and its root, and the skillful and its root. --MN9/Sujato

The terms used in the suttas are precise yet open to personal interpretation. Here are my interpretations:

• root is understood to be analogous to the root of a plant. A root emerges from a seed and supplies nutrients for the plants's existence. When plants are cut above the root, many will spring back to life. When plants are uprooted, they are gone and don't come back.
• condition is a necessity for something else. A condition for bread is warmth that encourages yeast to rise. Conditions are not causes.
• cause makes something happen actively. Yeast causes bread to rise if conditions are favorable.

For example, I would say that ignorance is a condition for delight to become the root of suffering. Even that statement might be inaccurate because it is possible (?) that delight simply would not happen for the Buddha. Delight does happen for me even though I am not ignorant of it or its effect. And delight still causes suffering for me even though I am aware of my ignorance.

This question goes too far. The Buddha taught greed, hatred & delusion are "roots" and did not teach about the "roots of the roots".

And what is the root of the unwholesome? Greed is a root of the unwholesome; hate is a root of the unwholesome; delusion is a root of the unwholesome. MN 9

Ultimately, the Buddha taught these are lead by "ignorance" and that there is no preceding cause of ignorance:

Monks, ignorance is the leader in the attainment of unskillful qualities, followed by lack of conscience & lack of concern. SN 45.1

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Bhikkhus, this is said: ‘A first point of ignorance, bhikkhus, is not seen such that before this there was no ignorance and afterward it came into being.’ AN 10.61

The above defilements are merely elements (dhatu) of nature (refer to MN 115; SN 14.12; AN 7.11). This is all that needs to be known.

All Buddhist teachings revolve around the same core, Dependent Co-Arising, usually described as the Twelve Nidanas.

Dependent Co-Arising refers to the process of development of informational (representational, semiotic) reality, starting with unconscious causational/informational tendencies, to basic inclings of rudimentary representation, to development of mind, to emergence of representational "entities", culminating in an idea of Self as Subject of experience and Agent of action.

This process grows hand-in-hand with (co-develops in conjunction with) development of behavioral tendencies for attraction, repulsion, and judgement in general (of things as "good" and "bad"). When these two things - the representational reality made up of entities and self - and the judgement-based attraction/repulsion - come to maturity, we end up having something that thinks of itself as a sentient being acting in a world of good and bad entities, trying to acquire the good, and get rid of the bad. But because the fundamental assumption this is all based on is false - because in fact the world is not made of fixed entities, and they are not inherently good (desirable) or bad (undesirable), this situation leads to all kinds of turbulence, that to these so-called "sentient beings" looks like a valid struggle against trouble and suffering, towards some imagined idealized happy state. The funny thing though is, the more each of these "sentient beings" acts to obtain happiness for itself, the more trouble they (us) create for each other, and therefore for all of them (us). So to them (us) it looks like they (we) are trying hard to make things better, but in fact they (we) end up perpetuating this confusion and struggle.

This situation is the core condition of the vast amount of uninstructed worldlings. They (we) think their (our) subjective idea of the world is what the world is, and they (we) seriously try to act within it, only causing more trouble, endlessly.

The Three Roots are a distilation of the above to three basic tendencies in the minds of sentient beings. A tendency for assuming something as desirable, a tendency for assuming something as undesirable, and a tendency for taking subjective (representational) things at the face value as if they were objective.

It's kinda sad, if you think about it. Even tragic, if you ask me. Out of this vast field of energy develop formations capable of representation, and then these formations seriously think they need a new cell phone or a bigger breast. It would be comical if it weren't so sad.