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.
And the PineTime as an Open Source Smartwatch. I'm not using much of the fitness tracker functionality, but counting my steps is very important for me.
If a given form of data sharing is illegal, then you shouldn't be able to consent to it, especially now that we have awareness of dark patterns used to pressure people to consent to surrender their rights away.
The same reason a click-wrap TOS cannot be binding (as of 2020, I think) because it's too easy to run a contract by customer the length of Richard III and the end user give up and click without reading (or comprehending).
I have one. It does the bare minimum (show time, count steps, show notifications), everything else doesn't work very well, including the heart monitor. But the battery lasts for almost a month. And it's completely offline, no cloud services. I would still recommend it.
Apple is generally really good with privacy stuff. The health data stays on device unless you enable iCloud backup/sync. You can choose what app (if any) you’d like to share which part of your health data with (at which point you’re beholden by those app’s workflows and privacy policies). You can read directly from Apple here.
But the limiting factor is that you’d need to buy in to the rest of the ecosystem… or at least an iPhone. Not an issue for me, but YMMV depending on personal preferences.