Wouldn't the PowerPC-based PB G4 would be somewhat "incompatible" with the newer Intel-based Macs? I still have my G4 MDD, 10.4.11, 4 500GB HDDs, USB 2.0 PCI-card and FireWire 400, and I have trouble keeping it on my LAN since it uses an AirPort card, and even with wired Ethernet, it inexplicably "falls off" the network from time-to-time when I do get it mounted.
I know that machine is a dinosaur, but I simply love the pre-CS versions of Photoshop and Illustrator (7.0.1 and 10.2 respectively). I've got the CS4 Professional Suite on my 2010 i5 iMac (High Sierra) and 2012 i7 MacBook Pro (Mojave), but those versions are like going squirrel hunting with hand grenades. I've never had any issues with word processing or spreadsheet files since I no longer use the G4 for that kind of thing. (I must say, too, the G4 makes a grand jukebox when connected to my stereo!) And I love that machine, it was the most beautiful and best designed desktop Apple ever made IMHO.