[thesuperbigfrog]

>> Aside from Android/iOS, what other Smart Phone OSes have captured any kind of market?

At this time, none:

https://earthweb.com/wp-content/uploads/2021/11/image-119-10...

There are some non-iOS, non-Android phones such as PinePhone, (https://www.pine64.org/pinephone/) but they do not have any significant marketshare.