WatchControl

Control your Mac's media playback from your Apple Watch: Pause/Resume, change volume, forward/previous, mute/unmute. They talk to each other directly over bluetooth ... no logging in, no web services.
In order for the Apple Watch app to control your Mac's media, the companion Watch Control listener app needs to be running on the Mac. You'll find that in the Mac App Store.
Both the Mac and Apple Watch will need to be signed into the same iCloud account with Keychain syncing enabled. The app requires no login account and does not request to use or use the network.
The companion Mac app is free to evaluate for a trial period, after which there is a small ONE TIME in-app purchase in the Mac app to unlock it for all your Macs using the same app-store account.