You can think of this as the "Gold Master" release from Samsung. And that those that are not in the beta program should be getting the update within the next few days.
This update comes in as version N960FXXU4DSLB and weighs in at about 100MB. So it's a pretty small update for the Galaxy Note 9, but one that should be the last one.
Android 10 & One UI 2.0 has already rolled out to Samsung's 2019 devices
Samsung has already started rolling out this update to all Galaxy Note 10, Galaxy Note 10+ devices, as well as starting to roll it out to the Galaxy S10 lineup.
So the next device in line would be the Galaxy Note 9. And if it arrives just after the new year, that would be the fastest that a year-old smartphone has gotten a new version of Android. And that in of itself is pretty impressive to say the least. Seeing as year-old devices sometimes don't even get the next version of Android.
The update to Android 10 is a big one, when it does start rolling out. It's going to be nearly 2GB in size, so you'll definitely want to make sure that you are connected to a WiFi network, before beginning the download.
Samsung has turned things around, when it comes to updates
It wasn't that long ago that Samsung was terrible with updates, and many were unsure if their brand new Samsung smartphone would get the next version of Android.
Now, Samsung has turned into one of the faster OEMs at pushing out a new version of Android. The Galaxy Note 10 got its version about three months after it was released to the Pixel lineup. Which, is still somewhat slow, but it is much faster than it used to be. And that's a really good thing for Samsung and Android as a whole.
With the Galaxy Note 9 due to get its update in just a few days, it really shows that Samsung is serious about updates and wants to make sure that its smartphones are getting them in a timely fashion.
It also would not be all that surprising to see Samsung push the Android 10 and One UI 2.0 update to the Galaxy Note 9 on New Years Day or even the day after. As they do want to get this out there as soon as possible.