I have a hobby business doing something very similar, except I focus on a specific model—pretty much the most power efficient PowerPC desktop Mac you can get that can still run Mac OS 9, the Mac mini G4. It's at https://os9.shop
This made me remember that I've still got a G4 Mac Mini! I was bringing up a current Linux on it, last time I had it running. 2019, perhaps.
I need to fire it up...
TBH neither Ubuntu nor MorphOS was a patch on OS X, IMHO. Never re-set the machine up after emigrating in 2014.
But now, I badly want to get MacOS 9 running on it.... Sadly the machine is in my basement in another country, 1000 miles away, though.
Last time I was there, I managed with great effort to find my iBook G4. It runs fine. But it needs a new reed switch and the replacement process looks horrendous...
https://www.ifixit.com/Guide/iBook+G4+14-Inch+1.42+GHz+Reed+...