One thing I’d really love is a self-hosted all-day heart rate tracker, but have yet to stumble on such a thing.
Using a Gadgetbridge-compatible device with Gadgetbridge? I use a Xiaomi Mi Band 7 for that purpose. Needs an initial connection to the Xiaomi-servers in order to extract a key, but you can do this with an account with a throwaway e-mail address, and after that you delete the app and pair it with Gadgetbridge. I sync data after a workout or once every two-three days, but you should also be able to keep it connected via Bluetooth all the time if you like that.
Using a Gadgetbridge-compatible device with Gadgetbridge? I use a Xiaomi Mi Band 7 for that purpose. Needs an initial connection to the Xiaomi-servers in order to extract a key, but you can do this with an account with a throwaway e-mail address, and after that you delete the app and pair it with Gadgetbridge. I sync data after a workout or once every two-three days, but you should also be able to keep it connected via Bluetooth all the time if you like that.