Debian is also still providing updated installation images for m68k machines:
https://cdimage.debian.org/cdimage/ports/snapshots/
Downside is you will need sufficient amount of RAM for the current kernel configurations.
We're planning a small footprint memory kernel configuration in the near...
I am the maintainer of the big-endian PowerPC ports in Debian and I am regularly building updated installation images which also work on PowerMac machines, both 32- and 64-bit systems.
The latest images can always be found here:
https://cdimage.debian.org/cdimage/ports/snapshots/
The...