[dragonwriter]

> Android is an OS – specifically, the AOSP projects result,

No, Android is a trademark which designates the branded, proprietary-but-open-core OS developed by Google and licensed to handset and other device makers.

AOSP is an open source codebase which forms part of the codebase of Android.

> So Amazon can’t do it in their Android apps, unless they create a special version for Google Play Android

There is no such thing; that's just Android. Pop

> Other Android distributions that are also excluded include MIUI, Replicant, LineageOS, CopperheadOS, and Androidx86.

No, those are other AOSP-derived OSs, which can run some subset of Android apps.