Do you have any reasons for wanting to switch your server OS, or is it more to learn something new? Either way is fine, but it might change what is more interesting to you.

I used centos forever, but only recently started slowly migrating everything to NixOS. I use NixOS for the OS and a few common things like VPN, monitoring, etc. For all of my actual services, I deploy them using Hashicorp Nomad with docker.

I’m not sure i would recommend defining docker containers using NixOS. It’d be fine for a couple servers, but not great for a cluster where services can move around.