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.