I have a rack server in the garage with a gaming PC in it, 2 PSU's and the 2 GPU's mentioned, all running on Debian (which I soon plan to swap to nixos).

The AMD GPU's is passed through to a windows VM with 8 gigs or so of ram, for VR development in the garage usually, but sometimes is streamed as well.

The second Nvidia GPU goes to my linux machine on Ubuntu just for ease of patched nvidia drivers, a couple virtual monitors with an xconfig like this, and is my daily driver with 16 gigs of RAM.

Both use Virtio drivers for disk, network, and anything else I'm forgetting, Pcie passthrough via KVM/QEMU on the host.

I'd say the latency hangs around 5ms when streaming both at once, and never comes close to saturating the gigabit connection, but I'm sure some optimisations could be done somewhere along the line.

Clients run on anything from an Xbox series X to a random PC, hopefully soon an orange pi (worried about latency though).

When I have a workload requiring both GPU's I just keep 2 moonlight windows open and use the keybinds to unfocus the mouse then alt+tab to swap between them.

I don't have any complaints, although one time when my thermal setup was worse I left 2 copies Subnautica running for my wife and I to at Nitrox together, and it did start to drop in fps on the Linux machine once we picked it up after an hour or 2 running the games AFK.

Edit to add I'm mostly using this for gaming right now, but its handled everything (within reason) that I've tossed at it, but I'm planning on soon setting up this sometime soon also across a couple other PC's, but as of right now the VM's feel as if they're entirely distinct PC's from an external perspective