AFAIK the only way to achieve this is to pass-through a GPU via VT-d. This config does not appear to support this though. If you search github for this line, you will find other configs that support doing this- https://github.com/kholia/OSX-KVM/blob/master/macOS-libvirt....
Edit: It's relatively easy- blacklist (or uninstall) GPU drivers from host machine, and pass the PCI address to qemu. Performance is not perceptibly different from native. Other things you probably want to do are enable hugepages, pin virtual cpus to physical cores, and use vfio for network- https://github.com/pmj/virtio-net-osx.
It's also possible to run boot OSX using UEFI mode, which removes the need for the binary blobs in this repo.
Edit: It's relatively easy- blacklist (or uninstall) GPU drivers from host machine, and pass the PCI address to qemu. Performance is not perceptibly different from native. Other things you probably want to do are enable hugepages, pin virtual cpus to physical cores, and use vfio for network- https://github.com/pmj/virtio-net-osx.
It's also possible to run boot OSX using UEFI mode, which removes the need for the binary blobs in this repo.