Gos on Pixel 7, Switzerland carrier.
- Install Play services.
- Install Google Messages and disable RCS in the app
- Give SMS, phone, contact and network permissions to Google Messages
- Give Network, phone, SMS permissions to Play Services.
- Install Shizuku and app opps. Enable wireless USB debugging with Shizuku.
- Force close Messages and Play Services and clear cache.of both.
- Give the read device identifiers permission to Play Services.
- Open Messages, enable RCS. It will connect in minutes (I would say max 1h).
- You can remove device identifiers permission to Play Services and uninstall App Opps and Shizuku.
It disconnected after a few weeks. Do the trick again and it will reconnect.
I did not touch any setting in the Google settings in the parameter.