Thank you for mentioning Gadgetbridge [1]! Interestingly enough, i find people mentioning Gadgetbridge under very many recent smart band/watch/gadget related articles here on NH.

Gb is under constant development - improvements and new devices are being added all the time, thanks to the main developer who is really good with the deep BLE stuff. The app provides a great value in notifications (and their filters), steps/sleep/activity collecting and visualizing, button actions and more. We are looking for help, however, with some of the obvious things like nicer activities listing, simpler imports of data exported from other services etc, so feel free to stop by the Matrix chat or on Codeberg/Github.

[1] https://blog.freeyourgadget.org/

I'd never heard of Gadgetbridge, but "local storage" would certainly be my requirement. It's the same issue as smart-home devices (without voice control): from a user viewpoint there's absolutely no benefit to having them phone home.

GadgetBridge main website:

https://gadgetbridge.org

Looks interesting, hadn't come across it before.