@jw7, have you tried Qubes OS 4.0.4? That will probably work.
Try to install one of these:
https://ftp.qubes-os.org/iso/Qubes-R4.0.4-rc1-x86_64.iso
https://ftp.qubes-os.org/iso/Qubes-R4.0.4-rc2-x86_64.iso
https://ftp.qubes-os.org/iso/Qubes-R4.0.4-x86_64.iso
If 4.0.4 can’t query the variable store, then try 4.0.3. That will definitely boot.
https://ftp.qubes-os.org/iso/Qubes-R4.0.3-x86_64.iso
You won’t get some of the hardware virtualisation features, but you’ll more or less get the majority of the Qubes OS experience.
The problem is that Qubes 4.1 needs some CPU functions that the custom-designed CPUs put in Apple hardware simply don’t have. That’s partly why it could not query the variable store at boot, because it simply isn’t there inside the CPU…
Well, it’s never too late to start, and once you get comfortable, you’ll wonder how you ever did without it 