Is there a reason why the native A/V player for iOS/tvOS isn’t used? It seems like that would give the best playback results, and a consistent playback UI. Also better remote support. Then you wouldn’t need to worry about building in features for video codecs or troubleshooting issues there, you could just rely on Apple to make sure those things are functional. Things like Atmos or spacial audio are exposed via OS updates.
An interesting thread here with some additional thoughts: https://www.reddit.com/r/appletv/comments/szhak5/the_lastest_iteration_of_the_tvos_native_av/