Any Alexa device can control your Fire TV
 

You'd think that Amazon would have made it possible to control a Fire TV from external Alexa devices as soon as it was an option, but no -- you've had to use the Fire TV itself if you wanted to play a video using your voice. At last, though, sense ha...

https://www.engadget.com/2017/07/12/...ntrol-fire-tv/