3rd Party Hardware Apps on the Apple TV App?

You don’t download apps from the TV app. You download them from the App Store.

There is no forum block list.

Your approach is seemingly also somewhat unusual. Why not ask the app developer? Which implies other issues might be lurking here, among your client, the tvOS app developer, and you.

Apps installed onto and for iOS and iPadOS can present their content via the Apple TV app, but the apps must be installed. The Amazon Prime Video app for iOS and iPadOS, for instance. Once that or another app is installed, the content is then (also) available via the Apple TV app on the local system.

Deployment of the app can be via the tvOS app store, via the iOS and iPadOS app store, or via the enterprise deployment path, etc., depending on local requirements and expectations.

An older overview: https://developer.apple.com/library/archive/documentation/General/Conceptual/AppleTV_PG/

It’s up to Apple which Apps they choose to feature or make accessible. If you can’t find it in search then it isn’t there. Assuming your client submitted it for approval in the first place.

You might find better answers in the Developers Forum https://developer.apple.com/devforums/

Then clarify your question.

Sorry I attempted to help you. Based on your original post, it seemed you were having trouble finding an app. Figure it out in your own.

You’re welcome