Samsung has started rolling out stable One UI (Android 9.0 Pie) update for the Galaxy Note 9, via android-hilfe. This update is currently rolling out in Germany, it may come to other countries very soon. The update is available for the One UI beta users in the country.
The stable One UI update is rolling out with software version N960FXXU2CRLT and comes with the January 2019 security patch. The size of the update is 95MB.
Previously, Samsung rolled out the Galaxy S9 One UI update to beta and non-beta users simultaneously.
If you want to check for the update manually, you can head into the Settings > Software update.
Note: We didn't receive the update on our Galaxy Note 9 device (Germany model - On One UI beta) yet, we will update the article as soon as we receive the stable One UI update.