nubia sub-brand just introduced its latest flagship device - the Z20. It packs some serious hardware with the latest Snapdragon 855+ chipset, up to 512 GB storage and secondary display around the back. The two screens can operate independently, for quick-switching between apps. The rear screen also doubles as an always-on display and can be custom mapped in games for added usability. The phone runs nubia's UI 7.0 on top of Android Pie. This is not the first time nubia has outfitted its phones with two screens as last year's nubia X also offered this functionality. Still it's a very...