amazon[.]com/gp/mas/appstore/android/faq?
theverge[.]com/news/616646/amazon-appstore-ending-android-support
Amazon's App Store could be sideloaded on Android devices, and to make it easier they included that capability in their app until Google blocked it. Their App Store will continue to be available for Amazon devices.
They're also doing away with the coins used to pay for apps in their store. February 20, 2025 is the last day to purchase coins, and after August 20, 2025 they will no longer work. If you have any coins after that the amount will be refunded.