The concept suffers a little bit with graphical applications. They don’t exactly have equivalents to stdin, stdout and stderr which you could pipe or read/write willy-nilly.

RetroArch isn’t far off from the philosophy I think, those emulation cores are pretty much independent projects plugged into a frontend. Unfortunately that default frontend is pretty clunky and doesn’t come with sane defaults for known ROMs. Or even sane menu navigation tbh, main menu and game menu looked way too similar last time I used it…