https://arstechnica.com/gadgets/2017/12/amazon-prime-video-begins-rolling-out-to-the-tvos-app-store/

Apple CEO Tim Cook announced the forthcoming appearance of Amazon Prime Video to the Apple TV earlier this year, but the launch kept getting pushed back for unknown reasons. Now, Amazon's Prime Video app is finally rolling out on the tvOS app store. The Prime Video iOS app was recently updated to version 5.0 and the release notes state that subscribers can download a separate tvOS app on their Apple TV to watch Prime Video content on that device.