Today HTC is rolling out Android 6.0 to HTC Desire 820 in Taiwan. According to sources, ROM version is 3.17.709.3. Upadte weighs big 1.22 GB download in size.
The HTC Desire 820 is powered by 1GHz octa-core Qualcomm Snapdragon 615 processor and it comes with 2GB of RAM. The HTC Desire 820 is a dual SIM. Android 6.0 will include many new features like Google Now On Tap, App permissions, smart battery Optimization doze and many more.
— Gingerbread (@Masini1491) April 25, 2016
You can see full Android 6.0 update eligible devices list & update release dates By clicking here.