The Samsung Galaxy Note 9 is now receiving its official Android Pie update. The update is version N960FXXU2CRLT and includes the January 2019 Android security patches.
It appears that the rollout is only happening in Germany right now. Now that the update is complete, though, hopefully we'll start to Samsung push it out in other parts of the globe soon.
The update to Android Pie is a big one because it brings with it Samsung's new One UI. A major focus of One UI is to help make the user interface easier to navigate, especially on phones with bigger screens like the Note 9. Samsung has done this by keeping the content that you interact on the lower half of the screen while putting the content you view in the upper portion. Samsung has also worked to improve the look of its software with One UI and is adding a Night Mode across the user interface.