Asteroid OS

https://asteroid.os/
Support level:

Pairing	Y
Notifications	Y
Calls	Y
Settings	N/A
Alarms	N/A
Sync steps and heartrate	N/A
Sync activities	N/A
Calendar	N/A
Watch face download	N/A
Firmware upload	N/A
Navigation	N/A
Battery status	Y
Music Control	Y
Sync Time	Y
Weather	Y
Find my phone	N/A