> they know they GPUs vendor

They even know the exact chip the GPU is derived from.

https://morph.zone/modules/newbb_plus/viewtopic.php?topic_id=6993&forum=3&post_id=77900#77900

> the PS3 would be slower than a G4 Powermac

I think that depends on the specific task and on the exact G4 PowerMac model's CPU and clock rate.

> it is possible that a PPC linux hosted version of AROS
> might be developed.

It's been there for ages ("linux-ppc-system"):

http://aros.sourceforge.net/download.php#nightly-builds