RX 5700 XT to RX 7800 XT upgrade woes

Great. I figured all that was needed was a newer kernel like I mentioned earlier.

Well, before I saunter off for the evening, I’ll suggest attempting to switch to a TTY during a normal failed boot (or via chroot) and installing the 6.5 kernel:

sudo mhwd-kernel -i linux65

…then of course reboot.