Proxmox or Docker?

It’s not mutually exclusive? I have a 3-node proxmox config on which I have 3 VMs running as kubenetes nodes to which I deploy containers. I also have some VMs setup for things which either don’t work well as containers or which I simply don’t want as containers (e.g. a couple Windows VMs for doing Windows things).

I understand that running things in a VM provides better security than running them in a container.

Not sure what you mean by this - containers are typically easier to secure as they’re minimalist. But I doubt anyone is using VMs because they think they’re more secure.