if someone on the DevOps team knows Nix, option 3 becomes a lot cheaper time-wise! yeah, Nix flakes still need maintenance, especially on the `nixos-unstable` branch, but you get the quickest disaster recovery route possible!

plus, infra flexibility removes random constraints that e.g. Cloudflare Workers have

There are a bunch of ways to manage bare metal servers apart from Nix. People have been doing it for years. Kickstart, theforeman, maas, etc, [0]. Many to choose from according to your needs and layers you want them to manage.

Reality is these days you just boot a basic image that runs containers

[0] Longer list here: https://github.com/alexellis/awesome-baremetal

Indeed! We've yet to go down this route, but it's something we're thinking on. A friend and I have been talking about how to bring Nix-like constructs to Kubernetes as well, which has been interesting. (https://github.com/clotodex/kix, very much in the "this is fun to think about" phase)

This is what we do, I gave a talk about our setup earlier this week at CfgMgmtCamp: https://www.youtube.com/watch?v=DBxkVVrN0mA&t=8457s

Option 4 as well, that's how we do it at work and it's been great. However, it can't really be "someone on the team knows Nix", anyone working on Ops will need Nix skills in order to be effective.

I'm a NixOS fan, but been using Talos Linux on Hetzner nodes (using Cluster-API) to form a Kubernetes Cluster. Works great too!