How much prep time does the monorail get?

Your description reminds me somewhat of my current favourite podcast. You might enjoy at least some of their episodes I think. :) https://www.weirdstudies.com/

Good app. I use daily.

I can tell you that this is called demonym, but I don’t know the answer to your question… The Wikipedia page has a long list of suffixes, but no rules: https://en.m.wikipedia.org/wiki/Demonym