I'm aware hardware support on Qubes has been problematic for some users. Luckily, it's looking to get a lot better with the up-and-coming Qubes R4.1 (currently on it's first release candidate). It will be shipping with a fully updated base hypervisor and kernel feature set to allow support for newer hardware.
I'm not quite sure the specifics of your hardware problem, but, feel free to file a bug on the Qubes issue tracker.
I have been wondering... Instead of exposing the hardware GPU to the appVM, would a Vulkan virtualization work? I.e., VM sees a Vulkan API that forwards calls to a dedicated graphics VM that runs them.
(I understand that getting windos to use them could be hard.)
Yes, I was wanting to try this on a spare laptop but having to trial on a bunch until one works is going to be challenging. Is there a place to find supported hardware?
I actually care very little about anything other than the network stack. If audio doesn't work, it won't bother me.
You're in luck, there exists exactly what you're looking for. It's called the Hardware Compatibility List (HCL), see here: https://www.qubes-os.org/hcl/
FWIW I've run Qubes on a few random Intel laptops years ago and it just worked on all of them. (Including on an esoteric milspec laptop which oozed hacker-street-cred at the time).
There is a hardware compatibility page with user reports.
The main thing is that, to be practical, it needs at least 16GB of RAM. With only 16GB, you will want to use the ZRAM swap driver on your linux VMs. Dunno if any equivalent exists for windos.
OK. My personal recommendation is, don't even try with a machine smaller than 16GB, and expect to need to manually apportion memory between VMs if you have less than 32GB.
I'm not quite sure the specifics of your hardware problem, but, feel free to file a bug on the Qubes issue tracker.