Hi David,
Welcome to the forum, and thanks for posting! Your assumptions that Amazon “are totally not accepting new TV channel apps at all” or that an app “has no chance of being reviewed” are not accurate. Amazon Creator was simply one of the tools developers could use to quickly create video / media apps for Fire TV. With that service deprecated, you can still use any other available frameworks / SDKs / etc to create your media app. For example, you can use Android Studio directly, or use Cordova, or React Native, or any other of multitude of frameworks that can produce an Android app. Once submitted to Appstore (assuming there are no issues with it), your app should then become available for your users to download. I hope that answers your question.