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?
Outside of Google, the RCS APIs are currently only available for pre installed System apps.