MangoPenguin
The default Unbound server on Opnsense.
HDMI should auto-detect the best supported output automatically, is it not doing that?
Proxmox is good as a host OS, you’ll set up a VM for docker and run your stuff in that.
It has a built in backup system to image your VMs and Containers, you can combine it with Proxmox Backup Server either in a VM or on another system for incremental backups and deduplication.
As far as Nextcloud goes I’m not surprised you had issues, their setup is weird, non-standard and very unstable in my experience. I switched to Syncthing long ago and it’s so much better.
Sometimes you need a VM. They’re not overkill, just useful for different things.
Examples; Running Windows, Running OSX, Passing through hardware to use isolated from the host (PCIe devices, USB, etc), Linux guests where you need a full kernel and permissions (for example to run Docker without issues caused by being nested inside a container).
VMs don’t really have much more overhead than a container in most use cases too. For example a VM with debian installed uses about 30MB of RAM.
Maybe Intel AMT running? I’m not sure it can be disabled though.