I'm surprised at the other responses that you have received.

RCS isn't a Google only thing. And it isn't an "app". It is disappointing that people don't understand that RCS is a great replacement for SMS/MMS.

It really isn't. SMS did not support adding random mobile numbers to a group chat and blasting them with spam. Someone needs to either fix RCS properly for current day use-cases or it just needs to go away.

It had the potential to be a great replacement if it just worked™ like SMS/MMS (well, MMS was also quite fickle back in the days), given it's so brittle across devices even on the same OS, with little means of troubleshooting by end-users and even less from non-tech savvy users, it's kinda dead in the water.