Well you would be surprised then, most of them still supports 32-bit. There's talk at mailing list of debian-powerpc about firefox for ppc32 (still has some issues).
Gamed on an Apple TV Gen1, which is x86 32-bit (unfortunately some games ran very slow due swap on hard drive and less than 256MB ram)
I understand it's not the same thing as G4. Don't have a Power Mac G4, only Mac Mini G4, tried linux once but felt very limited with OpenGL 1.3 or 1.4 expposed from Radeon 9200 (iirc dhewm3 doom 3 port is GL 1.3 could run this one), most projects require OpenGL 2.x minimal, then returned to dualboot setup (OX X Tiger + macOS 9). Now the PM G4 my theory is, maxing to 2GB ram, get the dual cpu model, I think there's CPU swap or OC 2GHz for PM G4, and adding one of these AGP cards: Radeon HD 2500 PRO, Radeon HD 2600 PRO/XT, Radeon HD 3450, Radeon HD 3650, Radeon HD 3850, Radeon HD 3870, Radeon HD 4350, Radeon HD 4650 or Radeon HD 4670, should have OpenGL 3.2 on linux (as long running Mesa 24.1.6, after this version mesa 24.2.x they broke something).
PowerPC still a thing in Europe due Amiga, some of these ports are being able to run on big-endian devices thanks to some people from amiga scene, amiga x1000 and x5000 they're powerpc64 but 32-bit userland due to the U-boot bios, so they run 32-bit version of the applications.
Best regards,
Link.