RushFPV the makers of the Rush Tank VTX also make receivers. They also made this FrSky receiver of very small size. Full telemetry supported including RSSI. So your Betaflight LUA scripts will just work. This receiver is FrSky compatible and also has an SBUS output.
Because the receiver and antennas are very small, it is very suitable for a Whoop. But also suitable for a 5 inch quad.
Weight: 0.8 gram