Take a look at the models that Gadgetbridge supports. Your data stays on your phone. There are no servers to connect to. You should have roughly the same experience on any Android device.

As for tracking sport sessions, look at what each model offers. I use it to sync my PineTime and Mi Smart Band 7.

I really like using the features that Mi Smart Band 7 has to offer AND knowing my data stays on my phone instead of going to servers in China.

Caveat: Recent Amazfit/Mi devices have needed you to set up the device in their proprietary app first to generate a pairing key.

There is safety there, but you’re just as safe using the the developer’s own repository for their apps, like NewPipe, Collabora, or the Guardian Project.

Something worth noting is that F-Droid is both an app to download other apps but they also maintains a repository of apps. You can use alternative store apps (like Droid-ify) with the F-Droid repository OR you could use the F-Droid app with a different repository (like IzzyOnDroid). You can mix and match to meet your needs.

I use the Droid-ify app with the F-Droid, IzzyOnDroid, microG, NewPipe, and Collabora repositories.

Once you start down this rabbit hole, give Obtanium a look.

The Smart Band 7 with Gadgetbridge is great! You can track a ton and your data stays on your devices instead of being sent to China. Unless that’s your thing. You be you.

I have a PineTime and a Xiaomi Smart Band 7. There has been little work done on sleep tracking for the PineTime using InfiniTime.

I’m tracking my sleep using the Smart Band 7 and Gadgetbridge not Xiaomi’s app. You do have to use Xiaomi’s app to set up the band the first time, but that’s been the case since the Mi Band 4.

Xiaomi’s bands combined with FOSS Gadgetbridge is an excellent combination.