Multiple sources have reported Apple working on an 18.8-inch foldable iPad or MacBook, and a leaker today reports that theres a prototype of the device with Face ID embedded beneath the display.While more than one supply-chain source has pointed to signs of an 18.8-inch folding display, differing views have been expressed about whether the intended use is for an iPad Pro or MacBook Display analyst Ross Young was first to suggest Apples interest in a 20.x-inch display, which he described as being for a MacBook.We are now showing Apple in our roadmap for foldable notebooks. We hear there is interest at the largest size yet, around 20.x. This size could create a new category for Apple and would result in a true dual use product, a notebook with a full-size keyboard when folded and for use as a monitor when not folded and used with an external keyboard.Apple analyst Ming-Chi Kuo found evidence of a large folding display in the supply chain, at the time saying it was 20.3 inches diagonally. He too said it was for a MacBook.Kuo later said that Apple was instead considering a somewhat smaller 18.8-inch display, and this new size was later backed by Young, who said the exact size was 18.76 inches, which Apple would round to 18.8 inches.Fast-forward a few months, and Jeff Pu added a third voice, though by this time it was unclear whether the intended use was in an iPad or MacBook.Prototype unit has embedded Face IDLeaker Digital chat station who posted accurate leaks about the telephoto lens coming to the iPhone 16 Pro (after previously being exclusive to the iPhone 15 Pro Max) and the larger sensor in this years main camera now says that there is a prototype of this folding display with Face ID tech embedded beneath it.Guoguo also has a Foldable iPad Pro, an engineering machine with a 18.8-inch screen, using a metal superstructured lens, mainly integrating Face ID Rx and Tx for under-screen 3D face recognition.Apple does have multiple patents for this tech, and was recently reported to have solved the biggest problem.By this point, theres plenty of evidence that Apple is experimenting with some kind of foldable 18.8-inch display the question is: Is it for an iPad Pro or a MacBook?An all-display device would instinctively point us to an iPad, and this still seems the most likely bet at this point. While Apple does have patents relating to an all-screen MacBook with soft keyboard, the company would need to solve three separate problems to make this workable:Making a non-physical keyboard comfortable to useSimulating the feel of a physical keyboardMaking it compatible with touch-typingThe company has ideas for solving all three problems, dating all the way back to 2018, but implementing them still seems a stretch even within the uncertain launch timings for the mystery device.There are also those who believe Apple is working on a single hybrid device which can run both macOS and iPadOS. While Im sure prototypes of such a device exist, the company has consistently said that it sees them as different products intended for different usage.Id expect in-display Face ID to launch in an iPhone ahead of an iPad, but the timings are currently vague enough for this to remain possible.Add 9to5Mac to your Google News feed. FTC: We use income earning auto affiliate links. More.Youre reading 9to5Mac experts who break news about Apple and its surrounding ecosystem, day after day. Be sure to check out our homepage for all the latest news, and follow 9to5Mac on Twitter, Facebook, and LinkedIn to stay in the loop. Dont know where to start? Check out our exclusive stories, reviews, how-tos, and subscribe to our YouTube channel