If you plan on designing anything for the new Apple TV OS then you’ll likely want to start with a UI kit. This will save a whole lot of time recreating default elements & give your design a native feel.
The kit may seem rather simplistic but it contains everything you’d need to create an Apple TV application. All the major screen displays are included with blank templates for each one.
These settings have been set forth by Apple and in time they may change. But currently it’s best to follow along with these guidelines and see where they might lead.
Few developers have latched onto the new tvOS release which was announced back in Apple’s September 2015 event. Over time I think we’ll see more focus on this area and hopefully even greater support for default UX advancements just like iOS + OS X.