The Polar Sensor Logger App has MQTT support. We installed Home Assitant on a Rasperri PI and tried to connect the Polar Sensor Logger App:
https://petergamma.org/polar-sensor-logger-app-by-jukka-happonen-polar-electro-oy-research-center/
to Home Assistant. Unfortunately, we failed. Has someone managed to connect the Polar Sensor Logger App to HA?