Regarding sleep tracking, have you seen the Sleep Log app?
Also in its to do list there's this:
Enable receiving data on the Gadgetbridge side + testing. Help appreciated!
So hopefully it's not too long before gadgetbridge can receive the data.
@Ganblejs started
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
Regarding sleep tracking, have you seen the Sleep Log app?
Also in its to do list there's this:
So hopefully it's not too long before gadgetbridge can receive the data.