ok - "generation" is actually irrelevant. It's a marketing term. What matters is that you use apps that are compatible with your operating system ,which is fire OS 6.3
my very last word: that XDA article is a mess - it refers to OS6 as being based on Nougat
everywhere else you see android 6 = marshmallow, 7 = nougat
e.g.
https://en.droidwiki.org/wiki/List_o...n_names#Nougat
Lollipop
5.0
5.1
5.1.1
Marshmallow
The android version 6.0, announced at 17th of august in 2015 is called after the sweet Marshmallow.
Nougat
Android 7, also called Android N, officialy got the name Nougat.
Oreo
Android 8, also called Android O, carries the name Oreo, which are two crispy chocolate cookies with a vanilla cream center.
that's all from me, expect to offer a different google search result:
https://www.techjunkie.com/install-g...n-fire-tablet/