https://wccftech.com/android-pie-rolling-out-for-the-galaxy-note-9-on-sprint/

Now that most Galaxy S9+s globally are already running Android Pie, carriers in the U.S are focusing on the Galaxy Note 9. The only S9 variants yet to receive the update are the ones on T-Mobile and the carrier-unlocked ones. Xfinity debuted the rollout followed by Verizon, Sprint and AT&T. In the Galaxy Note 9’s case, AT&T beat everyone else by being the first carrier to update their devices a few days ago.

Today, the Sprint Galaxy Note 9 Android Pie update is now rolling out. Multiple users have reported receiving the OTA update notification on their handsets. Sprint is rolling out firmware version N960USQU1CSAA for the Galaxy Note 9 on its network. The update weighs in at 1.9GB and comes with the January 2019 security patch. You also get all the standard OneUI features including a system-wide dark theme, a redesigned UI for several apps such as Samsung Messages and a lot more.