The new Amazon Prime Video app for Mac lets you access the subscription catalog as well as the movie store from where you can rent or purchase movies. It also supports PiP, AirPlay and downloads.
Amazon on Apple Mac
It is native macOS app that can be downloaded from the Mac App Store. It supports Intel-based and Apple Silicon-based M1 Macs running macOS Big Sur or later.
You can access the subscription catalog included with your Amazon Prime selection. You can also rent or purchase new movies and TV shows from within the app – much like the Apple TV app – with payments made through either your Amazon account or Apple's in-app system.

Amazon Prime Video for macOS
The app supports AirPlay, download for offline viewing, Picture-in-Picture (macOS native) and Amazon's X-Ray feature. It lists 'UHD' on movie pages but we are getting maximum 1080p HD streaming on a 2019 Intel-based 5K iMac.
Amazon Prime Video was already available on most other popular platforms including Android TV, Apple TV, FireTV, Smart TV, Roku and game consoles.
The app can be downloaded now from the Mac App Store.