This is probably a pretty good use of a LLM. Music is supposed to be mathematical patterns which seems good for a computer to predict. It would be easy to pre-c

This is probably a pretty good use of a LLM. Music is supposed to be mathematical patterns which seems good for a computer to predict. It would be easy to pre-categorise music like "Amiga" or "C64" or "FM synth" or whatever, so you could generate music more like you want. However, like you said the existing library is so unimaginably huge, just get an existing library and put it on shuffle. That will run on a potato and needs a lot less resources.