Question: Is it possible to expose the HRM to Apps like OpenTracks (Like Huami devices on Gadgetbridge)

My idea was to scan for the log files of the recorder app and parse them into activities. For this to work, gadgetbridge would need to pull and parse these files from the watch. However, I have no experience with Banglejs programming, so I don't know whether that's possible.

Do you know how to do the part on the Gadgetbridge side though? If so I wouldn't have to do as much trial and error maybe :p

Another alternative would be to expose the HRM sensor as smart Heart rate measurement device.

Same for this, do you know how - even if just on Gadgetbridge side?

@Gordon has added this commented code when integrating Bangle.js and Gadgetbridge:

public boolean supportsManualHeartRateMeasurement(GBDevice device) {
        /* we could do this, but the current code for onHeartRateTest
        looks completely broken. There's no way to stop heart rate measurements
        and it doesn't even appear to care what device it's getting the current
        heart rate measurements from. Fixing it is too much work so disabling
        for now.
         */
        return false;
    }

But that's probably not really the same thing you're talking about.