I’m using a commercial desktop with an i5 Sandy bridge. I maxed out to 32Gb of ram only because I’m running trueNAS, debian with containers, and home assistant. Most RAM goes to trueNAS and trueNAS doesn’t accurately report ram. For CPU, mostly just task limited but I don’t really think thats a proxmox issue. Obviously it’s not going to support an enterprise or even small business but it works for what I need of less than 4 users on my budget.
Proxmox doesn’t really ask for much but I probably would recommend docker for your arm devices.