Polar Sensor Logger app by Jukka Happonen, Polar Electro Oy Research Center

Jukka Happonen, Senior Specialist at Polar Electro Oy Research Center made an app, the Polar Sensor Logger app, which can record many parameters from Polar sensors to .txt files, and can stream sensor data over MQTT to Influx Data Base. The Polar Sensor Logger app seems not to be an offical Polar app, but it is an easy and contemporary solution for sensor data streaming:

https://play.google.com/store/apps/details?id=com.j_ware.polarsensorlogger&gl=CH

You can also develop your own application using the Polar SDK:

https://www.polar.com/en/developers/sdk

https://community.home-assistant.io/t/polar-sensor-logger-app-over-mqtt-to-home-assistant/424955