The whole landscape of health trackers is depressing. I bought a fitbit last year as I could expend it at work, and I ended up leaving it in a drawer exactly for the uneasy feeling of sharing very sensitive data. Health data is probably the most impactful on personal lives (insurances, banks, etc.), and it's astonishing to me how it's too much to ask to a company that makes watches to have watches as their mine business model.
I understand sharing data for further analysis etc., but I should be able to use my health tracker locally, only talking to my phone app and nothing else, similar to how gadgetbridge works. I was eyeing banglejs specifically to be able to do this, even though it's not really a health tracker.