The latest version of Tasmota (9.2) now runs on an ESP32 and, by using setoption115 1, it will scan for BLE beacons and report them via MQTT. The dev boards will run off a microUSB so could, in theory, be fitted in every room.
I’ve never used tasmota before. Does it work with multiple devices in different rooms?
How reliable is the RSSI for distance estimation? Any chance of using it for triangulation?
Then we could use this as a multipurpose, maybe ble, lux, pir, temp.