[ashlar]

I just have a maybe stupid question, I read that:

Can't be implemented

1. Passthrough audio not working - Not supported by Microsoft for 3rd party apps
   

So, how is it possible for Netflix to provide Dolby Atmos out on the Xbox One X? Is Netflix not also a 3rd party application?
Or do they have an other solution?

Thanks     

    Dolby Atmos is a specific case. There's an app for Atmos, that you have to download and that enables Atmos for Bluray playback. Netflix is quite likely in "the same boat" and has access to system calls usually reserved for "full games", not UWP. Microsoft has an history of expanding UWP capabilities, so maybe we will see it available in the future. But that's nothing anybody can promise.