score:6
The most relevant documentation regarding this situation is the following vague statement in Ryanair's terms and conditions:
6.6 You must produce valid travel documentation matching the details on your Boarding Pass for all flights ...
So the question is what Ryanair considers "valid travel documentation" and if the name in the travel document matches the name on the boarding pass.
Depending on the route and the passenger's citizenship, Ryanair accepts different kinds of travel documents. You can find the complete list here. Important for this question is that a Danish driving licence is not a valid travel document. The only travel document accepted by Ryanair for Danish citizens is a passport.
Then the next question is if the name "Oliver Doe" matches the other name "Oliver D. Smith". You seem to argue that there is just a minor difference in the abbreviation of a surname, but in addition to that, the second surname is completely missing. Out of three names in the passport, just one of them is correct in the ticket reservation.
Since there is such a significant difference in the names on the passport and on the ticket, I would even doubt that other air lines would let you board in this situation, unless they don't do any id checks on their passengers at all or out of goodwill might have had accepted the Danish driving licence as id.
Knowing Ryanair's policies of fleecing their cargo where ever possible, I would absolutely not expect such a deviation in the name go unnoticed or be accepted at check in. The Ryanair name change fee is 110β¬ per booking (e.g. for both flights). A name change is possible up to four hours prior to departure.