As laid-out by Apple in this document, iTunes demands a MOV-container for any immersive audio streaming content (even 5.1 is “immersive” for them).
Is there a straight-forward way to export to MOV directly in Nuendo nowadays, or is the only way to do this the detour via Apple’s “Compressor” (or another 3rd party tool)?
As far as I understand so far, they do not require MOV-container for any immersive audio streaming content.
''For Dolby Atmos, additional requirements include:
Dolby Atmos master file must be provided as a BWF ADM file.
All audio tracks must be 24-bit LPCM audio at 48kHz’'.
However, ‘‘The QuickTime .mov file extension is expected for immersive 5.1 and 7.1 audio content’’.
No way to export .mov from Nuendo directly asof this moment. However, third party free tools like Davinci Resolve can do it for you.
True. 
As there’s no way to have my room certified by Dolby I can’t deliver official Atmos mixes anyway, so this wasn’t on my radar. Thanks for the correction.
… and thanks for the hint towards Resolve! I’m aware of several ways to create MOVs, but I was hoping to avoid the extra steps.
As far as I understand it the official position of Dolby changed recently, so you don’t need official certification for all deliverables. I could be wrong about this but I think this changed.
Very interesting info Mattias. Thx
Yes Matthias is correct.
Dolby certification for all home entertainment Atmos ended at New Years.
The only remaining Atmos certification is for cinema.
Huh!!! That slipped my attention, somehow. Great news! Thanks for the clarification, @MattiasNYC and @ErikGuldager . Will search Dolby’s website for an official announcement.
If the video streaming platforms like Netflix does not require Dolby Atmos certified studio, an audio streaming platform like Apple Music most likely does not require such certification either.