What if this capability was built into the official version of Cemu, but (!) with some sort of basic ownership check included? I'd imagine that if it's possible to pull games directly off of Nintendo's servers, there's a good chance it's also possible to query which games an account owns.

As far as I know, nobody ever looked into this. There's no interest.

If emulator developers want people to use their emulators legally, I think there are some more creative avenues that could be explored. Not in all cases, but at least in some of them.