I just called up Netflix support & they confirmed that this player (nor any Panasonic player or TV prior to this year) has a Netflix App which supports Atmos. They also said they weren't aware of the possibility of updating Apps that were already on players. If the App was downloaded however, they say it can be updated...Does this make sense? To me, an App's an App, whether it originally came on the player or if it was downloaded.....
I did notice the TV programs only list "5.1" audio on the UB820 Netflix App, whereas those same programs on my 2019 Panasonic TV & Apple TV 4K list "Atmos" audio.
Did I read right though, that some here have actually got it working? Now that's the confusing part. Maybe a firmware did some magic with the Netflix App???