Feature Request: Support for R-R / HRV Data Logging in .FIT Files

Hi Hammerhead Team,

I would like to request a feature for the Karoo 3: the option to log raw R-R intervals (HRV data) directly into the generated .fit activity files.

Current Limitation:

When connected to a heart rate monitor that transmits HRV data such as the Polar H10, the Karoo currently only logs aggregated 1-second heart rate (BPM) data into the activity file. The raw R-R interval data sent by the sensor is discarded. Why this feature is important: Many cyclists and endurance athletes rely on R-R intervals to perform advanced physiological analyses post-ride. Specifically, tracking DFA alpha_1 to determine the aerobic threshold (VT1 / LT1) on platforms like Intervals.icu requires raw R-R data stored directly in the FIT file.

Proposed Solution:

Add a toggle in the settings (for example under Sensors   -> [HR Sensor] or within Profile Settings) to enable "Log R-R / HRV Data". This addition would make the Karoo 3 an even more powerful tool for sports science and endurance training, eliminating the need for complex workarounds or secondary devices.

Thank you for your continuous work on improving Karoo OS!