According to there, the Note7 is also the only Android working system

As for Amazon, their support web page represents support for HDR content on the Universe Note7, which, as we know, was accomplished shelves last season.

According to there, the Note7 is also the only Android working system Samsung Galaxy S8 Specs os program that has HD play-back support while all other Android working system os devices get only SD.

We will tell you from our Universe S8 that we do have HD play-back support but there is no HDR support yet (this has been corroborated by other Universe S8 
Samsung S8 Clone users on reddit). We have no details about when Amazon will start running HDR content on the Universe S8.

As of now, neither the G6 nor the S8 have any official HDR content available for consumption. Let's wish Smash hit on the world wide web Amazon movie the switch because it's not as if there isn't any HDR content out there; it's just not being designed available for cellular yet.