After distributing its beta version to American S9 and S9+ devices at the end of November and updating international versions of the phone earlier this month, Samsung is now releasing Android 9 Pie and One UI to Comcast’s Xfinity S9s. That's a bit of a coup for Xfinity, as we're not accustomed to seeing a smaller carrier's version updated first, especially not before unlocked handsets.
Updating to version G960USQU3CSAB brings all the benefits of Android 9 Pie, One UI, and the January security patch in a single download. While other American carriers haven't confirmed when they'll update their versions of the Galaxy S9 and S9+, this is hopefully an indication they should follow soon.
Xfinity users will automatically receive the update over the air once it's available. If you haven't been prompted for it yet, you can manually force your phone to check for it by going into Settings -> Software update -> Download updates manually.