WHOOP has been around for a long time, focusing on the analysis of sleep efficiency. Of the several devices I have tested, this is the most convenient. I think a combination of your analyses would be interesting.
Hello Konrad, the API seems to be opened, but the data they are providing are aggregated, we need a direct access to the sensor data, so we can perform our analysis in real time. This API only sends the information about which sleep phase they already estimated.
I used to use the Pebble Watch with your app. Now I miss the data (HR) because I use WHOOP (and this is unlikely to change 
). I’m uploading combined screenshots from both apps.
Just wanted to mention - WHOOP also has a “HR Broadcasting” mode in which the whoop band broadcasts the heart rate via ANT+ and BLE. That should be the raw data and work