http://wccftech.com/amazon-fire-os-nougat-version-6/

Amazon’s Fire OS powers the entire range of Fire tablets and streaming devices from the maker. Today, Fire OS has got updated to version 6, which brings Android 7.1.2 Nougat on board. This update is pretty major for the OS as it brings features like Picture-in-Picture (PiP) functionality to Fire TV, but sadly, the update will be limited to just a few Fire OS devices.

The update was first spotted by the folks at Android Police as it appeared on one of Amazon’s developer pages. The company did not offer much information in the changelog, but it does mention the new version on Nougat to allow “checking permissions at runtime and linking to private libraries.”