I think Apple TV 4K settop box will be most used for gaming on a settop box because Apple TV 4K is more powerful than most cheap lowend Android TV and other settop box brands like Roku which may mostly be used for playing video, pictures, and music files from a storage drive like USB flash drive, SD card or video is streamed from the internet.
Nvidia Shield TV settop box which run on Android TV may also be popular with settop box gaming.
Nvidia Shield TV settop box which run on Android TV may also be popular with settop box gaming.