Currently supported:
- Wear OS by Google Smartwatches

Features (may vary depending on your watch):
- Lock your phone from your watch
- See phone battery status on your watch and vice versa
- Get a notification when any of your devices is charged or on low battery
- Do Not Disturb sync
- Manage apps installed on your watch from your phone
- Everything has a toggle

Find out more, and check out the source code here: https://github.com/boswelja/SmartwatchExtensions