What’s the issue with new ones? Proxmox should work just fine on new hardware.
I’m rocking a Dell Wyse “thin client” that cost rather less than any comparable N150. It’s fanless, still gets firmware updates (via LVFS!), and takes about 5W at the wall plug.
if you have to ask, mine was too new and had to settle for a non-LTS Ubuntu Server. it works, but I can't wait for LTS in a few months.