OnePlus has released the latest Android Pie-based Open Beta (OB) ROM for its latest flagship series. It is known as the OB3 and OB11 for the 6T and 6 respectively. These OBs claim to bring increased detail to the stock weather app, as well as the January 2019 security patch. Finally, it may improve on Google Duo integration on these phones.
https://www.notebookcheck.net/New-Open-Beta-for-the-OnePlus-6-and-6T-has-been-released.394681.0.html