LG certainly has the necessary technology to make a transparent foldable a reality. LG Display, which is a nominally independent company but obviously has a great working relationship with LG Electronics, has been demonstrating rollable OLED screens and transparent displays for quite a while. If you're wondering why LG persists with its unprofitable smartphone efforts, one good reason is that every new LG phone can serve as a tech showcase for the broader corporation's advances.
The transparent foldable design set out in LG's new patent is notable for one other reason: the hinge. A substantial part of the accompanying imagery is dedicated to the hinge, which is quite the complicated piece of kit. Other companies, like TCL and Huawei, have also been super secretive about their hinge technology, and it does appear like the mechanics of the actual folding and unfolding will be a point of differentiation when foldable devices do eventually become a reality.