https://wccftech.com/android-pie-beta-for-galaxy-s8-and-s8-plus-released-stable-build-rolling-out-globally-for-the-galaxy-s9-and-s9-plus/

Now that the Android Pie rollout for Samsung devices is in full swing, it was only a matter of time before the beta program for Samsung’s 2018 flagships would begin. Yesterday, Samsung unveiled the Android Pie beta for the Galaxy Note 8. It was only a matter of time before the Galaxy S8 and S8 Plus would get theirs, and it’s here today. Interested users can sign up for it via the Samsung Members app.

So far, the notice has been spotted only in India and Korea, but it is only a matter of time before it goes live in markets. Those who are interested can sign up by opening the Samsung Members (Samsung+ in the US) app and tapping on the hamburger icon on the top-left on the screen. In the notices tab, you’ll see one that says “OneUI Beta”. Tap it on it and sign up for the program. After some time, you’ll receive a firmware update on your phone bearing versions G950FXXU4ZSA5 for the Galaxy S8 and G955FXXU4ZSA5 for the Galaxy S8+ respectively.