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/
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
Studies have shown this for half a century. Microalgae are also proven water cleaners. Yet they are not applied large scale anywhere. There are a few microalgae based fertilisers on the market whete I live though!