There is no requirement from Sonos to be connected to an eARC port to get standard Atmos, it is carried via Dolby Digital Plus. Dolby Digital Plus is small enough in bandwidth to be carried across ARC, and is in fact the format most streaming companies, including Netflix, use, when sending an Atmos signal. The exception is Apple, which tends to use Dolby MAT, which, when properly used, needs the bandwidth of eARC. But it’s fairly easy to change the output of an Apple TV to Dolby Digital Plus, and it will alter anything sent by Apple into Dolby Digital Plus on the fly.
Noted for your advises.
my current set (12years already ) also have a spec for Dolby Digital specification but max with Netflix can achieved 5.1 from Sonos app display. So since it is my next updates, I would like to caution for this features during replacement.
Since it’s not HDMI-ARC/eARC, maybe is your settings that prevent you from getting Atmos on Netflix - if indeed this is your problem?
Just checked Prism 65AL, actually Year 2022 no eARC and this is updates for 2024. This latest update have eARC port now.