we have no particular requirements towards the K8s master nodes - COS works fine, but so should everything else.
On the worker nodes you can also use most distribution, with a few caveats:
- you need to run
containerd as container runtime - others like Docker or cri-o do not work
- some features, namely “root access” (enabled view feature preview) do indeed require Ubuntu. There is work underway to remove this dependency.
We are also currently working on a Platform Support Matrix that would clearly list which platforms/K8s/Linux distributions we support to which degree.