OPPO has announced that there is now a "Trial Upgrade" of ColorOS 7 for the F11 smartphone series. This OS is based on Android 10, and is the first version to become available for these devices. Their users can apply to join this new beta via their Settings menus.
https://www.notebookcheck.net/OPPO-unveils-an-Android-10-beta-program-for-the-F11-and-F11-Pro.448919.0.html