I've been running proxmox. I haven't run windows, but I have ubuntu vm's with full hardware gpu passthrough. I've passed through nvidia and intel gpus.

I also have a macos vm, but I didn't set up gpu passthrough for that. Tried it once, it hung, didn't try it again. I use remote desktop anyway.

here are some misc links:

https://manjaro.site/how-to-enable-gpu-passthrough-on-proxmo...

https://manjaro.site/tips-to-create-ubuntu-20-04-vm-on-proxm...

https://pve.proxmox.com/wiki/Pci_passthrough

https://blog.konpat.me/dev/2019/03/11/setting-up-lxc-for-int...