You also probably didn't change the interfaces to virtio, because you wouldn't be able to install Windows without the virto drivers (if you changed the interface).
Just find yourself a serial key. Although qemu now is better. Not from a usability perspective but a driver one. You can mount drives directly as boot drives very simply
You know how Wine & Proton maintainers agreed & made things standardized with UWLGL (now umu-launcher)?
Can this be done with gamescope?
Like collaboration between Chimaera, Nobara, Bazzite & others into 1 standardized gamescope? Standardized Gamescope would contain device quirks & that kind of stuff as a great base, while still making it possible to fork it & include your own vision of how gamescope should work in your image.