GrapheneOS I think it's unclear in the announcement that you should grant the phone permission to google play services.
It mentions "granting the required permissions to Google Messages" and "access to the official Google Messages app which then also provides the official Play services app with the same access" makes it seem like permissions on Google Messages are sufficient.
My RCS is currently on 3000, please wait activation is in progress, I'll report back in the morning. I granted phone permissions to GPS and Google Messages.