[pintxo]

What I want is a way to collect heart rate and activity, ideally without a display, as I'd like to continue wearing my nice Swiss automatic watch. This device should stream all the information into the iOS health app, I explicitly do not want to store it off-device on some vendors cloud I have no idea if they are long-term trustworthy.

The closest I came to it was something from Garmin, rather small but with a display. I stopped using it as it became apparent that their data privacy policy was awful, I either could consent to everything or their app would basically be useless. This is over 1 ago, they might have changed the policies, don't know.

I have surrendered to the market now and got an Apple watch. It at least ensures that the data is not spread to additional companies, as apple has the data anyway. It's a nice product, but honestly mostly a gimmick for me.