

The drives should work fine, for standard blurays and self wrote disks. There are a mature cli utilities and often the gui version is just a frontend for the cli tools. It is just an optical drive otherwise.
Arch Linux Wiki : https://wiki.archlinux.org/title/Blu-ray
Check out makemkv, which has a cli option, and their forum for compatibility for 4K blurays. Newer bluray drives have additional protection for 4K if I understood correctly.

I installed Linux on a G5 quad. I would expect the iMac to work as well. I think I installed Alpine, but I haven’t started it up in a while. Produces a lot of heat. You’ll need the big endian PPC version btw.
Edit: That screen is not a G5. Linux will run just fine on the Intel macs which that screen is showing.