I’ve got 2 I’m using:
Running proxmox, 2-3 vms, 5-8 lxc, with decent headroom. Not sure about 4k/HDR though.
Running just 4 VMs: opnsense, adguard, unifi controller, and a fileflows transcoding node. This might be worth looking into, since it has Intel Quicksync and can transcode a couple 4k streams simultaneously no problem. I think there’s HDR support, but I don’t use it much myself.