Many operator tier Android TV launcher like zenterio Android TV launcher are very beautiful but I don't find any app apk for this. Some other are vewd tv, mi India patchwall, 3ready (3ss) launcher etc. Have anyone link of these launcher app apks (not present in play store) that can be used in Android TV. Zenterio launcher https://m.youtube.com/watch?v=zLC2py8x6JI
They most likely wouldn't work on other Android TV devices due to customized dependencies in that Android TV box's custom OS (like how Mi Box and Shield TV have specific customizations to the Android TV OS found in both).