Google is finally rolling out YouTube music to Wear OS watches but there is a catch. The app only works with Wear OS 3 which is for the time being exclusive to Samsung's Galaxy Watch 4.
As 9to5Google has reported, the app itself does not support streaming music and requires you to download songs to play them offline. Another problem is that downloading music is a "YouTube Premium feature" which means you are going to have to pay for a monthly subscription if you want to use the app at all.
The downloads themselves can only happen when you place the watch on the charging dock, further limiting the app's usefulness. Google does allow users to upload purchased music to private storage but this being Google, it's once again locked behind the premium paywall.
Either way you slice it, you are going to have to buy a Galaxy Watch 4, own music and then pay a monthly subscription to play it on the device. All of these hoops, for an app that doesn't even support music streaming.
What makes it worse is that most of the watches that run Wear OS 2 will not be getting the update to Wear OS 3, which means you are going to have to go shopping for a watch that will eventually get updated to the new OS once the Samsung exclusivity ends to even use the app.