@fireye
#Proxmox runs on Debian, not on Nixos. Nixos has a completely different file structure (no /etc, no /usr/bin). That would be a very experimental and uphill fight.
Of course you can run Nixos inside Proxmox VMs.
If you want too restructure your Docker setup, you can run containers directly in the Debian below Proxmox, as LXC in Proxmox or on any OS you like inside Proxmox VMs.
Running Docker inside VMs has the advantage that you can move them seamlessly between hypervisors once you decide to expand Proxmox to a cluster.