Not long after Verizon and T-mobile upgraded their Samsung Galaxy S8 and S8 + to Android 8 Oreo, Sprint is doing the same thing right now. Currently, the sprint version of the Galaxy S8 user has received an Android Oreo update.
This update is about 1.5GB in size, and the new version includes the Samsung Experience 9.0 interface (pre-installed in the new Galaxy S9 series).
It now appears that AT&T is still the last operator in the United States to update the Samsung Galaxy S8 mobile phone to Android Oreo.
Currently, the Samsung Galaxy S8 active version on Sprint, AT&T, and T-mobile has not received an Android Oreo update.