Yes, I read it. I started using your approach, gateway sensor ids representing nodes ids, but from the controller point of view this is not straight forward, I think. The 2 problems remain somehow the same. How to get the controllers to understand that gateway sensors are not actually sensors but RSSI value, and repeaters breaks my current algorithm.
Thinking more about this, if it is something the library would benefit, lead me to read about the RF24 and NRF5 radios. I only have RFM69 devices (20 nodes) and it offers RSSI out of the box, same as RFM LoRa version and NRF5. But RF24 lacks this feature. So it somewhat depends on how many are using radios with rssi. Library developers included RSSI functionality, so it has to be of interest.
The repeater problem is partially solved because RF24 networks need repeaters, but don't have RSSI. RFM networks should do without repeaters for most applications. For NRF5, I lack this info. But as I passed the rssi from transport to gateway transport, same can be done with actual sender from the header.
Maybe in version 3.0.0 something like this can be implemented? My understanding is that controllers get link quality data the same way they get all other data from devices, on other platforms. Mabey a I_LINK_QUALITY type can be added especially for this information?
for example my zigbee network:
zigbee2mqtt/device {"linkquality":5,"state":"ON"}