https://www.techradar.com/news/amazon-music-comes-to-roku-tvs-and-roku-streaming-boxes

Your Roku devices are about to get a real upgrade in audio playback thanks to the arrival of Amazon Music Unlimited on Roku OS. 

Music Unlimited joins Pandora, iHeartRadio and Vevo on Roku platforms, and fills the Spotify-shaped hole on Roku after that service left in December.