Wasn't it just a very expensive GPU which basically had a flag that enabled the feature in the driver?
I seem to recall reading about people unlocking their NVIDIA GPUs to allow the nested virtualization.
I'm not sure this does split up the GPU. One of the listed self-hosted requirements is "Your Nvidia GPU should not be attached to a running X display server." Sounds like exclusive GPU use to me.
--- Edit: here it is https://github.com/DualCoder/vgpu_unlock