Apple has given us Atmos through streaming, but that is a compressed version of what UHD BluRay provides. Apps like Infuse give users option to play our BluRay collection on AppleTV, which is great - However, AppleTV will not decode lossless Atmos TrueHD or DTS-X like Android and Xbox streaming devices. Blu-ray player Audio and Video quality is possible if Apple would give us the option, I would happily stay in AppleTV ecosystem for all my video consumption - and gladly upgrade my TVOS devices for this option - if you feel the same Infuse has started a change.org petition for Atmos TrueHD - https://chng.it/56SMZ2gSvf
True, but it wont pass along the Atmos metadata. Therefore, you´ll get Dolby True HD without any quality loss (as multichannel PCM), but lose Atmos in the process.