You can already do this, but the Apple’s EULA forbids Mac OS running (virtually or otherwise) on non-Apple hardware.
It's MY operating system after I bought it.
So what? The EULA can say whatever it wants.
As an individual developer I would totally violate that part of the EULA, but if I'm selling OSX computer like OP, you're exposing yourself to much greater legal risk.
Today you can run macOS and current Xcode in kvm/qemu on any modern amd64 server. Next macOS will be arm only and likely DRM’d up the wazoo.