The place nano is best is in environments which aren't otherwise setup for working on. e.g. a fresh linux install or some ephemeral server/container. If you can do this remotely e.g. with the VSCode Remote, great.

I'd suggest if you know a few vi keybindings, vi would be better than nano. e.g. navigating through the document will be quicker with vi than nano.

It's not that nano is bad, but for server administration you cannot be sure what exists on the other end, and due to security rules you can't always install what you want, except, there will always be vi. Nano might not be there when you need it (I have learned this the hard way).

It isn't, but frequently the default editor is set to vim. That said I would question the judgement of anyone that judges you based on your favored editor.

Except emacs, those folks will burn in hell.