Had some fun reading about the Nintendo GameCube & Wii architecture: https://www.copetti.org/writings/consoles/wii/
Beyond the new remotes & increased networking use (and ofcourse the casing!) those consoles weren't that different...
The GameCube did address I/O bandwidth issues Nintendo was having on previous machines by adding some circuitry inside the GPU to schedule I/O access. The Wii upgraded this to an ARM CPU running a microkernel, capable of emulating the old GameCube behaviour.