There's some stuff you can do, but a lot of it requires either the action replay disc with a wiikey adapter (which is just a memory card adapter for gamecube you can plug an SD card into) or a copy of smash bros and a modded savefile with the same adapter. Getting backups to run correctly is a royal pain in the ass, the few launcher apps available like swiss or gcos are picky about SD cards over 2GB, so if you're running a 1.2gb gc backup, it's one at a time and the down-ported apps from the wii homeberew versions like vbagx, hugo, fceux, and genplusgx run ok, but again you need a specific directory structure, and depending on how many roms you want to throw on there you run out of that 2gb upper limit pretty quick again.
You can swap in a larger SD card once you boot to your homebrew launcher, but you're pretty much swapping stuff back and forth whereas with a wii you can run from ~32GB SD or ~500GB usb disk or a wiiu, with a ~128GB SD card without needing to boot something off a 2 gb SD card first.
So again, you CAN do it, but I more or less did it years ago because it's what a I had to work with, now I prefer to use a wii or a wii u running nintendont.