The Mi Mix Fold is Xiaomi's first-gen foldable phablet, and thus offers an 8-inch main display in a book-like form-factor. It has just been released for sale in China, which, according to the OEM, has been a complete success. Xiaomi claims to have sold all stock of the device for ~US$61 million in just 1 minute.
https://www.notebookcheck.net/Xiaomi-sells-30-000-Mi-Mix-Folds-in-less-than-60-seconds.532933.0.html