Virtio-mem for GPU Passthrough to share system memory?

Has anyone done GPU Passthrough using virtio-mem instead of virtio-balloon?

I’ve just realized that ballooning stops working also on Linux VMs when vfio passthrough such as a GPU device is added (using libvirt/KVM/qemu - not sure about lxd?).

Virtio-mem however seems to solve that? Any success stories would be wholeheartedly welcomed.