OnePlus has finally released official Android Pie to users of its latest flagship. However, it is an Open Beta, not a stock Oxygen OS (OOS) release. It has many new features of OOS based on Pie \e.g. gestures and a new UI), albeit with some bugs.
https://www.notebookcheck.net/OnePlus-6-now-with-official-Pie-in-beta-form.328716.0.html