The Galaxy S9 Android Pie update seems to be finally rolling out to carrier-locked devices in the US. The Galaxy S9 and S9+ on Comcast's Xfinity network are getting the Pie update as we write this, and we should see more carriers in the US – especially the big four – start releasing the update in the coming days. It's worth mentioning that the unlocked Galaxy S9 and S9+ don't seem to be getting Pie just yet, but that shouldn't be the case for long, either.
You can check if the update is available for your device from the Software update menu in the phone's Settings app. The update will show up on its own at some point, but that can take some time so it's best to manually check. If the update isn't available over the air, we have the Android Pie firmware for the Comcast-branded Galaxy S9 and S9+ in our firmware database (S9 | S9+) that you can flash using a Windows PC to get on Pie right now.
The update brings with it the January 2019 security patch. For details on what features and changes Android Pie brings to the Galaxy S9 and Galaxy S9+, check out our One UI (Android Pie) feature focus series.