New Android Pie beta update for Galaxy S9 duo is now rolling out in the US today. The update is a bit smaller than the previous ones. Anyways, the update list contains a very long list of bug fixes and general improvements. Also, the update has the current December 2018 security patch level.
Above all, as the update is rolling out in the US, you need to be the part of beta program for Android Pie in the US. The update weighs 589MB, and you may get the notification shortly. Updating the OS will bump up your S9 will on version G960USQU3ZRL5.
As part of a beta program, the update has a lot of improvements that come as feedback from the beta testers. Samsung may take some time to perfect the Android 9 update on its flagship devices before the final update that will roll out in January.
You can see the entire changelog in the image above. Note that the update is rolling out in phases, and it may take some days to all the users that are currently on the beta program of Android on Samsung.