From the announcement post
here:
You can use Alexa to start playing from Amazon Music, Amazon Music Unlimited, Pandora, iHeartRadio, SiriusXM, TuneIn Radio, and we’re working to bring Spotify controls in the future too.
Also, any Alexa device on your account can use basic controls, such as play, pause, volume, and skip, on your Sonos players. This works for all services and music on Sonos, started through the Sonos app. Mark good posts by pressing the like button, and select the best answer on questions you've asked to help others find solutions.