The fourth official beta for the Samsung Galaxy Note 9 is now available, albeit mainly to those users already on beta 3. This new update fixes touchscreen and keyboard bugs left in the preceding version. Therefore, it is not the best indication that an official update to Pie for the device will be here soon.
https://www.notebookcheck.net/New-One-UI-Android-9-beta-for-the-Samsung-Galaxy-Note-9-available.388611.0.html