Use proxmox and put the OMV system on a VM, use containers por everything else or just create a ubuntu VM with docker, and anything u like.
I use an old i7 860 for proxmox with 8gb of ram:
OMV has 2 cores and 3gb ram
Ubuntu with docker has 2 cores and 4gb of ram (just a couple of services on docker runnign)
a windows10 machine but its just for testing, is not running
and a Win2016 server for AD but its off too, just turn it on when i need a change on my PCs on network (i have a business).
So the disk, 120gb ssd for proxmox, 2x2tb (raid1 config in bios) for the OMV sharing media, etc, and 2x1tb (raid1 config in bios) for VMS, containers, etc
All work fine for me, i spend like 150$ including the disk. Lol