To create a bootable iso for powerpc (32 bit)

You will need to make a hfs file system in an img file using mac-fdisk or equivialent.

You should put yaboot bootloader on this hfs file system along with a minimal system (for installation) and
an installer.

https://tr.opensuse.org/SDB:PPC:_Booting_with_Yaboot_on_a_PowerMacintosh

https://forums.macrumors.com/threads/debian-sid-installation-guide-powerpc.2146795/

You should then make a hybrid HFS/ISO9660 image using mkisofs (but we should try using xorriso).

https://superuser.com/questions/647204/proper-options-for-mkisofs-to-create-hybrid-mac-and-windows-iso-image

The installer should create a 32mb hfs partition, and an ext2 partition for the rest of the disk

Yaboot should be installed in the 32mb hfs partition on the hdd

Debian unofficial ports powerpc repository is updated as of 14-Jun-2023, almost all other versions of linux
for ppc32 have been discontinued.

http://ftp.ports.debian.org/debian-ports/

The CD-ROM should be less than 700mb to fit on a CD (not a DVD).

Ideally, include a graphical gtk package manager, xfce and connman and also drivers

Create a script to install the rest from network connection.

See also:

https://wiki.debian.org/DebianOnPowerPC