What will AI find fulfilling itself? I find that to be quite a deep question.

I feel the limitations of humans are quite a feature when you think about what the experience of life would be like if you couldn’t forget or experienced things for the first time. If you already knew everything and you could achieve almost anything with zero effort. It actually sounds…insufferable.

You might find Stanislav Lem's Golem XIV worth a read, in which a what we now call an AGI shares, amongst other things, its knowledge and speculations about long-term evolution of superintelligences, in a lecture to humans, before entering the next stage itself. https://www.goodreads.com/book/show/10208493 It seems difficult to obtain an English edition these days but there is a reddit thread you might want to look into.