this isn't really a good list because some of these are just shit i downloaded for nostalgia or word of mouth, but it's not like there's zero games outside of the first-party stuff of interest, it's just a very rough era for early 3D gaming in many places and the N64 being difficult to develop for resulted in some notable stinkers. less of a needle on a haystack, more like a stack of hay that's good and usable, and a stack that's utterly fucked. and actually acquiring the good games might be a hell and a half for pricing nowadays. but the first party titles ARE pretty strong, honestly.
if you go buying a flashcart, the romhacks or something like the f-zero x expansion kit are worth noting.