Debian because it just works. I am interested in trying NixOS though.

You (Ken Langone) made a bad investment -> Take the L

For starting out I would suggest Longhorn, I’ve had several issues with it but maybe they’ve been fixed. I also used Rook Ceph which is overkill but neat to play with. Techno Tim has several videos on Kubernetes including setting up a cluster (he has an ansible playbook for it) as well as how to set up Longhorn.