The Mi 8 Explorer Edition's 'transparent' back is, sadly, a prop (video)7
Xiaomi announced the souped-up Mi 8 Explorer Edition back in the spring as it top-shelf handset, with FaceID-styled 3D scanning at the front, an in-display finger reader and... transparent back that allegedly showed the Snapdragon chipset beneath.
Well, that transparency turns out to be fake, as many suspected - the picture was just too neatly arranged to be true for anyone who has peeked inside a smartphone's innards.
As you can see in the video above, the "transparent" back is simply a prop that can be scrubbed off, and the real innards aren't nearly as aesthetically pleasing as Xiaomi would like you to believe. This leaves HTC's U12+ as the one with the really nice transparent back, though it doesn't look nearly as impressive as painted stuff on the inside of the rear cover.