@typhlosion gamecube homebrew is extremely a thing, there are plenty of popular games (including melee) with exploits that let you launch software from special memory card files and hardmods that can do basically anything up to and including replacing the disc drive entirely
the reason wii homebrew was so big so fast was that it's basically a funny gamecube, and so it benefitted from a healthy gamecube homebrew scene. a lot of wii homebrew (GCMM comes to mind) is one project with the wii and the gamecube as supported compilation targets