While some variants of the 2017 Galaxy S8 and Note 8 phones already have the Oreo operating system, not all carrier/country variants have been hit with Google's latest update.
Samsung wrote over the weekend:
We understand that many of you have Unlocked Galaxy S8/+ and Note 8 devices and may be wondering why those with Carrier models are seeing the updates first. The reason for this is that Unlocked devices must go through more rigorous testing than Carrier-specific devices because we need to make sure there is proper network functionality across ALL supported networks ...
With this being said, we're working with our Carriers to get Oreo out to ALL eligible Galaxy S8/+ and Note 8 devices within the next 2-3 weeks.
Google touts Android Oreo as providing a "smarter, faster" version of Android. Samsung began pushing Oreo in February. However, the update had a glitch and was pulled. Samsung has been slowly rolling out a fixed version since.
Samsung launched its Galaxy S9 and Galaxy S9 Plus flagships with Android Oreo earlier this month.