Last week it became apparent Amazon had not included support for local encryption with Fire OS 5, which would seem to contradict its support of Apple's fight for encryption. Asked for comment on exactly that and why they would drop support when it seems all the work is done by Google anyway, an Amazon spokesperson simply told us, "We will return the option for full disk encryption with a Fire OS update coming this spring."
Amazon initially said its customers "weren't using" local encryption, so it decided not to include support for it, which appeared flimsy reasoning. Whatever the case, the company has wisely decided to change course, likely in light of how it looks currently.