Older Device? Don't Expect the Best Version
We can't predict which features Samsung will pick from Google's version of Android Pie and what features it'll bring over from its new UI (Experience 10) but we can say this: Samsung's Galaxy Android Pie updates probably won't be created equal.
If you own a newer device like the Galaxy S9 or if you're planning to buy the Galaxy Note 9, you've got nothing to worry about. Flagship devices always get the best version of Android and Samsung's Experience user interface.
If you own an older device, you might not get the full suite of Android Pie/Samsung Experience features. In most cases, features are held back due to software limitations or performance concerns.
For instance, Samsung held the Galaxy S7’s Always On Display feature back from the Galaxy S6 and Galaxy Note 5.
We expect Android Pie updates to be similar, but if you want the absolute best software experience Samsung has to offer (the most features, tweaks, etc), you'll want to buy the latest device.