We've announced our plan to add RCS with Messaging Layer Security (MLS) for E2EE compatible with Google Messages and iOS. SMS/MMS will only be a fallback once that's implemented.
unless it will work without Google account/Google play services, this will be just another Google messages app clone (why not use directly Google messages then?) or dumb SMS app without IM (if I'm not willing to use play services/Google account) and I have already plenty of those to choose from
