Hmmm. I still have to look into this further. For now I
NetGuard will have to block unwanted information exchange.
It's not only my Onyx Note Pro that might call home, but also my Hisense A5 Pro cc eInk mobile. Interestingly, this phone manufactured by one of China's state-sponsored/-owned firms also includes an app PayGuard that keeps telling me if apps have a permission that might be damaging my privacy: Like apps that send my location information even when they are not being used.
For now, it seems that the Onyx Boox ereaders and the Hisense eInk mobiles are safer than Samsung's Google services based devices. You can disable Google on Onyx and can't even install them on Hisense.
However, I still have to check with the devices running over a proxy, whether I am blocking all that I want to.