Every TV platform speaks a different language
Apple TV runs tvOS and Swift, Android TV and Google TV run Kotlin, Fire TV is Android-based but layers on Amazon services and its own store, Roku uses BrightScript, and Samsung Tizen and LG webOS are web platforms. There is no shared SDK that covers all of them. Sylvain focuses native effort on the platforms where it pays off most, tvOS and Android TV / Fire TV, and gives you a clear-eyed read on the rest.