Is it possible to go the other way? Make a PowerMac into a Nintendo Wii?
The Nintendo Wii notably has two processors that run different operating systems, so you might need some emulation or hardware modifications to do so
There's no point.
but why? :)
Not exactly what you're asking about, but related and from the same time period. The original Xbox 360 dev kit was a PowerMac G5.
https://apple.fandom.com/wiki/Alpha_Xenon_Development_Kit