Just wanted to chime in here with the results of some experimentation. I have a Pixel 8a on Graphene with a US Mobile eSIM on their Verizon network. I managed to use the AppOps method to get RCS working, after much bashing of head against the wall. This comment was the approach I used (it required granting Play Services access to device identifiers). RCS disconnected after a few weeks.
I had seen some additional comments that suggested the device identifier requirement was Verizon-specific, so I switched my network to T-Mobile this morning (US Mobile allows you to switch between the big 3). RCS activated almost immediately without any problems and no access to device IDs.
Bottom line - if you're on Verizon it's a hassle right now without granting Play Services the READ_DEVICE_IDENTIFIER permission via AppOps or ADB, as I think others have discovered. T-Mobile seems to work okay without that permission (though Google Messages still requires the identifiers, it seems). Just thought I'd chime in with my two cents.
