If I am not mistaken, GoogleFI uses multiple carriers, some of which may not support RCS, so it would make sense to not support RCS, if it is dependent upon which carrier you are actually on. My backup line is on Boost Infinite, which uses AT&T, so it appears that that line also supports it.Google Fi which uses T-Mobile. Someone that accessed Beta 1 code said NVMO not supported. Here are my thoughts as to why I don’t see it:
1. NVMO not suported
2. Required carrier update to device
3. I’m on a U.S. iPhone, US region settings, US carrier and located in the U.S. but logged in with my UK Apple account, so it might be locked to Apple account location.