I’ve recently switched from a Supervised install on my main machine (Dell Optiplex 990), to Proxmox running 3 VM’s - 1x Home Assistant and 2x Ubuntu 18.04 VM’s, one running Plex, MQTT, OVPN, Portainer, etc and the other running only Shinobi for CCTV recording.
The machine has an old i5 2400, and 16gb RAM (recently updated and ran well on 8gb). I give each VM 2 cores and 4gb RAM. Runs very well, so you don’t need an amazing machine to do lots of work. HA runs without issue on 2gb of RAM, and I’ve found that Plex rarely uses over 2gb as well.
I’ve also got my test machine a Dell USFF 780 with a dual core and 4gb RAM set up using Proxmox with 1x HA VM and 1x Ubuntu VM, also runs perfectly well.
The current state of where the Supervised install is going to end up seems to me that it won’t be worth using (and I think that is kinda the plan), so I think the Proxmox route is a good one.