Switch Online is a lot better than the last time I had it (a year or two ago). The Sega Genesis collection in particular is waaaaay better. Problem is, for Sega, you want to have the right controller. Old Nintendo games I can generally play with any modern controller, since they're all evolutions from the Nintendo designs anyway. Genesis on the other hand has a very specific controller design that I really like, and playing Genesis games with the standard Nintendo button configurations just feels wrong.
Of course, the Genesis controller for Switch costs $55. They're charging even more for the N64 controller. You can get similar USB controllers for PC emulation for like $25 (half that if you don't mind skimping on weight/quality). Of course, it's Nintendo, so their retro controllers have to cost way more. It drives me nuts. Would be cool if their controllers at least also worked as PC controllers as well.