Alarm alerts for doors over mqtt

Configuration
2

The automation would look something like this:

- alias: 'door alarm'
  trigger:
  - platform: state
    entity_id: binary_sensor.door
    to: 'on'
  condition:
    condition: state
    entity_id: switch.alarm
    state: 'on'
  action:
  - service: switch.turn_on
    entity_id: switch.siren

Your challenge is to extract the door’s status (binary_sensor.door) from the single MQTT topic rfswitch/rf that “currently receives all values”.

I suggest you review the following post where I described two ways to handle the case where a single MQTT topic contains information for different sensors:
Sonoff RF Bridge. Strategies for receiving data