i opened the music app on my watch, clicked the airplay icon, and i see all of my home devices (homepod, apple tvs) listed. even my mac mini is listed.
AirPlay is different from the desired functionality. It basically uses your mac as a remote speaker, instead of actually opening the music app on the computer and playing music there.
You can test this out quite easily: play any audio from your mac (YouTube, Apple Music, whatever) and then try to pause it on your watch. This is not possible.
Spotify Connect allows you to do this easily on the other hand.
Apple’s “home” app allows for a bit of that. You can control music on homepods/apple tv from any device. I don’t think you can control a Mac like a speaker, though. And I actually find it buggy as heck when trying to control a speaker from multiple devices - requests are constantly timing out, the UI doesn’t update properly with the current state, etc. In practice I always just use AirPlay and control it from a single device.
That is true for AirPlay, but AirPlay 2 works differently: It controls playback on a device (say, a HomePod) and all devices on the network see what is playing on that device and can control playback.
¯\_(ツ)_/¯ I don't. The only thing I see listed on my Apple Watch is my Airpods. I have an Apple Watch series 6 (cellular model), iPhone 14 Pro Max, three HomePod Minis, an Apple TV 4K, and an M1 MacBook Pro. All of these devices are listed under my Apple ID within macOS system settings, so I don't know what gives. I guess to Apple's credit, there are a lot of failure points that could exist beyond their control around WiFi connectivity. But the three devices I listed that can serve as Home Hubs should help alleviate this issue when, for example, my Apple Watch isn't connected to WiFi. Maybe I should dig into this more.
