Debian-Ports PPC
Debian officially supported the 32-bit Big-Endian PowerPC architecture from Debian 2.2 up until Debian 8. After Debian 8, it became POWER (64-bit Little-Endian PowerPC).
Debian 8 for PowerPC was the original distro choice of neagix, and can boot with all of his kernels, as well as the current Wii-Linux 4.5 kernel.
Unfortunately, Debian 8 is getting quite old, and is beyond it's EOL date, and as such, won't be supported by the Wii-Linux project.
Fortunately, Debian-Ports exists, and has a version of Debian 12 and 13 for PowerPC. Unfortunately, it does not work particularly well. It's lacking in software support compared to other options, and horendously slow on the Wii. It can take upwards of 20 minutes just to install a package.
If you want to install it anyways, you won't get support for it, though it can boot if you really want to for whatever reason.