This is actually one of my New Year’s resolutions lol. Right now, my backups are local and my offsites are a hodgepodge of cloud services (basically holding encrypted container blobs of my stuff). Not ideal.
I’m looking at signing up for rsync.net since a lot of my backups are done via rsync anyway. Plan is to keep my local backups as-is and rsync them to rsync.net.
RCS is a whole can of worms. It’s presented like a carrier services (and carriers are in the mix, though often just for authentication), but it’s really a Google service. With Android, RCS connects directly to google’s mothership.
I believe on iOS those go to Apple’s servers which “peers” with google. Maybe search the RCS endpoint for Apple and see what comes up?