[fredoralive]

AFAIK the Wii is still mostly in the "no OS" era, the game replaces the system menu in memory and runs in kernel mode. With Wii games official games use a standard set of libraries to do things like show the exit menu / battery level when you press home, but that's part of the game disc / binary, not from an external OS.

There is however the ARM coprocessor that handles things like Bluetooth, USB, crypto etc. (basically, most of the stuff the Gamecube doesn't have). This does run its own IOS[1] software loaded from flash that is isolated from the PowerPC side of things where the game is running.

[1] No, not that one. Or the other one.