This are my findings, including audio codec where possible, using an LG C1 OLED display and Denon AVR-S930 receiver and the Paramount+ app:
Roku Streaming Stick 4K (3820X) on Roku OS v10.5.1
Halo S1E1 - 1080p SDR, AAC stereo (only other option is AAC Descriptive Audio)
Star Trek: Picard S2E1 - 1080p SDR, 1080p SDR, DD+ 5.1 (other options include AAC stereo, DD 5.1, and AAC Descriptive Audio)
A Quiet Place Part II - 1080p SDR, AAC stereo (other options include DD 5.1, DD+5.1 - no Atmos, and AAC Descriptive Audio)
Amazon FireStick 4K on Fire OS v6.2.8.7
Halo S1E1 - 4K Dolby Vision, DD+ 5.1 - no Atmos (other options include Stereo and Descriptive Audio)
Star Trek: Picard S2E1 - 1080p Dolby Vision, DD+ 5.1 (other options include Stereo and Descriptive Audio)
A Quiet Place Part II - 4K Dolby Vision, DD+ 5.1 (other options include Stereo and Descriptive Audio)
Apple TV 4K (A1842) on tvOS 15.4
Halo S1E1 - 4K Dolby Vision, Dolby Atmos (other option is Descriptive Audio)
Star Trek: Picard S2E1 - 1080p Dolby Vision, 5.1 audio (other option is Descriptive Audio)
A Quiet Place Part II - 4K Dolby Vision, Dolby Atmos (other option is Descriptive Audio)
Which FireTV device do you have? My Firestick 4K only gives me DD+ 5.1, stereo, or stereo descriptive audio.
FTV4K Max. Included that information in my signature.
Audio Track Order on FTV4K Max for HALO on Paramount+:
Defaults to TRACK 1, which is 5.1 audio and you have to select TRACK 2 to get Dolby ATMOS.
Swapped out from FTV4K (2018) models a few months back. Pretty sure that Dolby ATMOS was available on the 2018 device as well, but back then it was with P+ movies and GUILTY PARTY P+ Original. Maybe it is something lacking with the recent HALO release only on the FTV4K (2018) model device. It could also be how your AVR is handling/supporting the ATMOS tracks from Paramount+. I can get ATMOS even without 4K on my 1080p projector on Paramount+ through an ATMOS soundbar.
I had the FireStick 4K Max, and had to return it due to its motion smoothing that I was unable to turn off.
What is really weird, is that on my Rokus, the movie "Rumble" does play in Dolby Atmos, but nothing else on the service does.
The P+ app (recent versions, including 8.1.13-210811300) on the FS4K (firmware 6287/3768) does NOT have Atmos availability for known Atmos-enabled content, at least in my testing (several TVs/AVRs), despite Atmos tagging.
Ironically, firmware 6287/3768 includes changes/enhancements to better enumerate Dolby Vision/Atmos support, including the new AV diagnostics menu option (which tests DV/DA support, among other useful functionality).
Even more ironic, the P+ app (same versions) on the O4KSB supports Dolby Atmos, even though the O4KSB doesnt have DD+/Atmos OS-level/EDID detection support, and only a DD+-level (non-Atmos) Dolby decoder.
The P+ app/AV content quality management is a moving mess, and always has been, and these coming/going again AV content quality issue relative to firmware/app updates impact every platform, and P+ clearly doesnt seem capable to the task (constant regressions of all kinds).
Same P+ version (8.1.13) on a FTV4K Max (Fire OS 7) is supporting ATMOS on available P+ content. Not sure what has changed in the FTV4K (2018; Fire OS 6) version recently. I moved to the FTV4K Max (Fire OS 7) because it became apparent that Fire OS 6 was never going to support ATMOS on Neftlix with they way that Netflix chooses to implement it.
The FS4k Max uses a different Dolby chipset than the previous FireStick 4K model.
Yes. Aware of that. It is why I traded in all of my FTV4K (2018) devices. FTV4K Max and Fire OS 7 has the ability to decode a Dolby ATMOS track, which is what Netflix requires. FTV4K (2018) and Fire OS 6 allows passthrough for the AVR or Soundbar to decode. Not sure why Netflix doesn't allow that as an option.
My Roku devices upgraded today to v11. As expected, the update DID NOT FIX THE ISSUE.
What devices do you have? I'm waiting for my 4800 to grab the os 11 update.