Sure you can. The question is what are the exact specs and what do you want to self-host?
I have two HP EliteDesk 800 Mini as a XCP-NG pool. Both with i5 6th gen only but with 64GB each and they run about 20 VMs distributed between both.
Sure they won’t be able to perform large language model tasks but for most self-hosted services they are more than powerful enough.