mostly, itd be handy to be able to link the gba up to a computer or something for game-dev reasons, so i can send arbitrary Stuff over the link cable while testing out a link protocol or whatnot
it'd also be cool to be able to use something like this to link a real gba to an emulated one and e.g. trade pokémon or do multiplayer shenanigans that way
but also... i want to make a piece of music software for gba, like lsdj or whatnot but taking full advantage of the gba's power and sample mixing and stuff, and it'd be great to have a "gba-native" way to do things like import samples and export tracks. and there's only so much you can do with that when you can't connect to any devices aside from other gbas