Earlier quoted context omitted.
I have had luck running CoD on a VM with GPU passtrough. It is not necessarily less cumbersome than dual booting though.
That is my next goal right right after I master NixOS! The learning curve is steep for nix itself and I know vfio is no walk in the park. I want to make sure if I'm doing complicated stuff like that, I can at least roll things back to a clean state if they break.
Have fun with the project; I'd be curious to know if (like me) you end up (sadly!) continuing to dual-boot for Windows only games. VFIO seemed like the dream end goal, and maybe it's gotten better since 2021, but for me at least, it got in the way more often than not.
I have rigged up a non-VFIO VM that boots off the same Windows partition though, so that I can log into it and run Windows updates once in a while without needing to do a full reboot.