I couldn't agree more on how restricted popular smartwatches are. I'm working on a project to capture the maximum physiological and health data—such as heart rate (HR), heart rate variability (HRV), stress levels, and SpO2—from a smartwatch in the shortest possible interval. So far, the best I've achieved is once per minute. Could pebble support obtaining this data (particularly HRV) at even shorter intervals?
I also tinker with health data from wearables. I've built some Whoop-like UIs for a couple cheapo wrist straps from Aliexpress, but their HR monitors are always so bad that they're useless outside of when you're sleeping.
