Apple is loosening its App Store restrictions, at least for Amazon, letting the company directly sell content to users through in-app purchases (via The Verge).
Amazon Prime Videos
Amazon Prime Video on iOS, iPadOS, and Apple TV now offer content to purchase. Apple’s guidelines normally forbid in-app purchases that aren’t offered directly through the App Store.
Renting or buying a movie or TV show uses the credit card you have on file with Amazon, rather than the card associated with your Apple ID. It appears to not require an app update, and users should start seeing a new store tab at the bottom of the screen.
You can download the Amazon Prime Video app here.