Flutter Monitor Bluetooth Distance

I am building a Flutter app that uses bluetooth to detect bluetooth beacons. I want to monitor the distance (RSSI) of the beacons continuously but I am not too sure how to approach this.

I am currently using flutter_blue. I am open to any new packages.

At the moment I am just scanning for devices.

_flutterBlue.scan(scanMode: ScanMode.balanced).listen((scanResult) {
      // scanResult.device.
      print("${scanResult.device.id} :: ${scanResult.device.name}");
      // check if uuid can be assigned to a gate
      if (!_gateOpening && !_preparingToOpenGate) {
        _userGates.forEach((manualGate) {
          manualGate.gates.forEach((gate) {
            gate.beacons.forEach((beacon) {
              if (beacon.uuid == scanResult.device.id.id) {
                print("found a uiid");
                if (gate.detectedBeacons.containsKey(scanResult.device.id.id)) {
                  gate.detectedBeacons[scanResult.device.id.id]
                      .insert(0, scanResult.rssi);
                } else {
                  gate.detectedBeacons[scanResult.device.id.id] = [
                    scanResult.rssi
                  ];
                }

                if (gate.detectedBeacons[scanResult.device.id.id].length >=
                    _config.minBLEDetections) {
                  gate.detectedBeacons[scanResult.device.id.id].removeLast();
                }
              }
            });
          });
        });

        //// only take readings further if gps is struggling
        if (_gpsAccuracy > _config.maxFineAccuracyLevel) {
          approachingBeacons();
        }
      }
    });