Designing for Android TV is not the same as designing for phones. Aside from the differences in control, there is also the standard Leanback UI that is prevalent in many TV apps. Google keeps supporting the Leanback library so that navigation between apps is consistent and well designed.
When designing an app, some people like to use software like Sketch to mock up a user interface before beginning to implement it. While there are plenty of templates to use for Android phones, there has not been templates designed for Android TV until recently. Liam Spraldin from Android Police posted seven Android TV UI frames that designers are free to use to mock up their app.
Hopefully designers will be able to take advantage of these resources to create high quality apps for the TV.