Are there any (preferably FOSS) RCS/SMS/MMS apps as an alternative to Google Messages? I can’t convince anyone to switch to signal and would like to at least use an app that I trust. Eventually I’ll be moving to a privacy-respecting mobile OS so I’ll need an SMS app to run without Google Play Services, but I don’t want to totally miss out on RCS. Are there any alternatives? Is this even possible?
It is an Apple problem.
Don’t confuse a client API with a cross platform protocol. They are different beasts and Apple refuses to send or receive RCS messages. That’s different than a client trying to send or receive an RCS message.
Apple is vetted as an authorized entity whereas a random client is not.