Is there any way to control Mac volume from Apple Watch?
I've used MacID with great success on my Pebble smartwatch but they also have support for Apple Watch. It's $4 but TOTALLY worth it!

https://macid.co/

The watch app requires the companion iPhone app to sync with the desktop app and control the volume and track selection. 

And that's not all, the iPhone to Mac has a proximity sensor so you can set your computer to unlock AS YOU APPROACH IT and lock if you get up to walk away. 

I hope this answer helps :)