This was it, basically.
I removed the GPU totally. Turned on the machine, Qubes loads up normally, everything works. Didn’t even reinstall Qubes… Qubes was running fine all along, it just had no display after the login screen. So I am going to edit part of the title to reflect what the final issue was for ease of reference, in case a user ever has the same issue.
It should be noted somewhere that Asrock Intel Arc B580 Challenger 12GB OC GDDR6 does not work with Qubes, or at least it did not for me.