After looking through all of the documentation, I beleive that there isn't a way to tell the Apple TV to start a particular appllication on startup.
For example, here is waht I'd like it to do:
If the Apple TV 4th Gen loses power, when it starts back up it automaically launches my app.
I would love for this to be incorpated in the OS. Are there any other devs who would also like this functionaity?