Hi Andreas, Recently nvidia-graphics-drivers/525.147.05-7~deb12u1~bpo11+1 got accepted into bullseye-backports. Thank you for your work on that.
Wondering why nvidia-kernel-dkms cannot be installed is that firmware-nvidia-gsp has component non-free-firmware, but which exists only starting in bookworm. I asked #debian-ftp and it looks this will require a new upload with adjusted component back to non-free. Regards, Salvatore