Samsung for a long time is working on Android update to Oreo version dedicated to their phones. In nearest future, after months of waiting finally first beta program for Galaxy S8 users will be launched. Samsung even confirmed which areas will receive it as first, and which countries will receive beta version in second batch.
For beginning beta version of Android 8 for Galaxy S8 will be available in the United Kingdom, North America and South Korea. Second batch will include China, Germany, Spain, France, Poland and India. If you want to test Android Oreo on your Galaxy S8, you have to register in Samsung Members app, and later you will be able to download new version of system from "Software update" menu located in Settings.