My understanding was that you have to install google messages to get RCS to work and on google's end it gets finicky about device ids. I read a couple blogs where people found RCS to be really unstable on GrapheneOS even with a couple workarounds.

If I'm going to have to install a bunch of google products onto my phone anyways, I don't buy the benefits as much.

I also had a recent experience being shaken down by a border guard entering Australia, and if he'd asked to go through my phone, explaining that I'm running a weird privacy focused OS he's never seen before seems like it would be a great way to increase my chances of spending a night in airport jail and being put on the next flight to North America. I don't really have anything to hide and appearing like I have things to hide could seriously inconvenience my life. Barring a tourist from entering a country has a very low bar of evidence.

Edit: Also the backup restoration is a bit more of a mess for me right now for the same reason I need the dual sim feature. I've got an American esim that's difficult to reactivate without being in America.