Peacock, a steaming service from NBC Universal which was released back in July 2020, is still not available in the official Amazon Appstore. There’s no telling how long this standoff will last, but for now, it is easy to sideload Peacock on any Amazon *Fire TV, *Fire TV Stick, Fire TV Cube, or Fire TV Edition television, by following the steps in this video.
*1st-gen Fire TV and 1st-gen Fire TV Stick are not compatible with the Peacock app.