Many years ago I had a Facebook account under my real name, and they blocked it and told me to verify … I did everything they asked and they wouldn’t accept it… I recreated it under a fake name (very obvious it’s fake since it uses a celeb name) and have been using it for messaging a couple of friends for like a decade now with no issue
Samsung messages was using RCS since 2012… Years before Google messages adopted it.
There are others out there that use it but call it by different names like “advanced messaging”, “SMS+” etc
Google was the first to add e2e encryption and push it hard though, but if you send a RCS message from Google messages to Samsungs messages app, it won’t have e2e, and most likely will be the same with messaging Apple.
But given how much Apple have fought to make it hard (or at least inconvenient) to message between them, and shut down any apps that made messaging between Apple and Android better, this is a big step for Apple