Nope, Estonian. Quite close to Finnish but not quite the same. We do have all the õäöü-s that we need though.

I apparently need to map more. My head had some Mercator perversion where Finland and Estonia were a continent apart. Or maybe I don't do spheres well.

Vietnamese uses the O with tilde charcater Õ, it's fairly common.

The first word I can think of is ngõ

https://en.wiktionary.org/wiki/ng%C3%B5_h%E1%BA%BBm

A Møøse once bit my sister...