If you run your stuff in containers then Proxmox (I aways install it on top of Debian) is your hypervisor is your base system
I believe you’re missing my point. Cockpit also works as an hypervisor for most people, a very light and stable one, besides…
If you’re running containers on Proxmox then you’re running LXC containers… why not just use LXD/Incus (also another hypervisor) to manage those containers that is considerably lighter, comes by default in the Debian repository, was designed to manage LXC container (not hacked around like Proxmox was) and isn’t mostly made by a for profit entity that sometimes likes to hold important patches on their subscription-only repositories? Or constantly nag you to buy a subscription?