Not yet.
Seems not a “limitation due to no subscription”.
Anyway… some topics are talking about Proxmox
https://community.nethserver.org/search?q=Proxmox%20KVM
There is a wiki install guide for an older version of Proxmox
https://wiki.nethserver.org/doku.php?id=userguide:install_nethserver_on_proxmox
and an idea to create a safe and accessible installation on a ProxMox-based service provider.
https://wiki.nethserver.org/doku.php?id=ns_networking&s[]=proxmox
Hope this could help but… this should be a different topic.