A Dutch blog claims to have unearthed patents filed with the Chinese intellectual property office (SIPO) by the OEM OPPO. They show a mobile device that is clearly foldable. The documents show that the company is considering either a notch or punch-hole technology for its purported first flexible display.
https://www.notebookcheck.net/More-new-OPPO-patents-showing-foldable-phone-prototypes-emerge.421183.0.html