On paper qemu should be able to do this. The hard part is hardware acceleration for the GPU. Without Apple putting effort into supporting this with e.g. documentation, that's a bit hard. That's also holding back linux support on Apple hardware. But it's a fixable problem that will only get easier as hw gets better and faster over time.
> The hard part is hardware acceleration for the GPU
Is it, though?
How Hard Can It Possibly Be to just do a software GL renderer that emulates a mid-2000s Radeon, these days?