Is there currently a way to control a Mac's audio volume from the Apple Watch?
I use AirPods paired with my Mac to play audio. Unfortunately, Apple didn't provide a convenient way to adjust the volume of the Mac from the AirPods1. I realized that the Apple Watch might be able to work as an interface for changing Mac volume instead.
Unfortunately, I haven't found any good way yet; i.e. Apple didn't provide Watch functionality for system-wide Mac volume adjusting. The only somewhat-way I've found is if audio is playing from Mac iTunes, and the iPhone/Watch is paired with that library via Home Sharing. The volume can then be changed with the Watch Remote app – but that doesn't trigger system-wide volume. It only changes iTunes' in-app volume.
Is there perhaps some third-party software for iOS/WatchOS that can accomplish this?
Note about iPhones: I know that the iOS app BTT Remote can control a Mac's volume, but unfortunately there is no Watch app for it. I don't wear an iPhone at all times while at home, but the Watch is on my wrist.
1The only way I know of is to invoke Siri on the AirPods and tell her to "lower the volume by x percent".