Music options

Tidal is not an Apple product, so you would have to ask Tidal when they are going to support the Apple Watch.

Pandora has rolled out support for the Apple Watch with Streaming for Cellular models, Offline playlists you can download for GPS only models, and Apple Watch Siri integration.

And of course Apple provided streaming, offline play, and Siri integration as well.

All other music services have not shown up. Spotify, often asked about, just using the Apple Watch as a remote control for the iPhone Spotify app. I have not hear of any other music vendors offering any Apple Support beside Pandora and Apple.

Spotify does not directly support the Apple Watch. But there are hacks to get offline music onto the Apple Watch. All that Spotify provides is an Apple Watch remote control app for their Spotify iPhone app.

I don't know what Napster does, and it has not come up in discussions in these forums that I remember (but lots of traffic on these forums, and it could have easily slipped by).

Pandora and Apple seem to be the only 2 streaming services that are going "All In" on the Apple Watch.