Going by the notion "better late than never" HTC's 2014 smartphone, the Desire 820 is getting the Marshmallow update. However, it is not clear that the update is available to how many regions for now. For the Desire 820 owners, please check your device if it has got the update.
As per our info, the update will tweak the Sense UI version to 7.0. As we always point out in our update-related articles, these updates are rolled out in a phase-wise manner so it might take some time to hit every device. You can also check for the manually by going to the setting > about phone > check for update.
The Marshmallow update will bring features such as Doze mode, Google Now on Tap, App permissions, and much more. If you own a Desire 820 then please let us know if you got the update through the comment section below.