Sharp has thrown its hat into the foldable-device ring by displaying its own device built around a flexible OLED panel. This screen will apparently measure 6.18-inches and have a 1440 x 3040 resolution when part of a finished product. Interestingly, it takes a clamshell form-factor and folding action, which is also associated with no companies besides Motorola at this point.
https://www.notebookcheck.net/Sharp-teases-its-own-foldable-phone-prototype.416219.0.html
What? Did Sharp ever make OLEDs? JDI's just making the jump (too late IMO). A thick body could mask the screen's inability to fold flat and makes the folding mechanism much easier to design and manufacture, but there should be other issues...