As I say in the post:

> You can always uninstall the app once done setting it up.

So no need to rely on 3rd party servers.

I also mention that you can use GadgetBridge if you want to store your own data locally.

Oh nice, I missed that bit, thank you! Saw the mention of Gadgetbridge but didn't know that meant it's usable offline. I've only ever used it for upgrading Pinetime firmware iirc

That makes this a seriously good option, I was looking for this a while ago but didn't find anything besides Pinetime, so I ordered a Pinetime and found out the heartbeat sensor is about as accurate on my wrist as tarot cards (I know it works for a few people, but most seemed to have the same issue). Everything else I could find back then was cloud-based or didn't do health tracking (or, n=1, didn't support Android)