In July 2018, OnePlus had announced that it will be skipping Android 8.1 Oreo on the OnePlus 3 and the OnePlus 3T and updating them to Android Pie directly by the end of the year. As 2018-end came close, CEO Pete Lau confirmed that the updates will be delayed as developers need more time to work on the Android Pie update for these phones. Now, two months into 2019, OnePlus has confirmed that the update is incoming, but it will follow the security patch update set to roll out soon.
On a forum page populated with queries regarding the OnePlus 3 and OnePlus 3T Android Pie timeline, OnePlus community manager David Y confirmed that the company will first roll out a security patch based on Android Oreo, and then roll out the anticipated Android Pie update. He also posted a tongue in cheek comment stating, “Can't you guys just go and do something more meaningful than chasing the update...(facepalm).”
There's still no specific date or timeline for the Android Pie rollout, but once you get an Android Oreo-based security patch update for your device, the Android Pie update should arrive soon. OnePlus has been quite responsive with respect to queries regarding the delayed update from OnePlus 3 and OnePlus 3T users.
To recall, OnePlus 5 and OnePlus 5T users received the update in December last year, while OnePlus 6 got the update in September 2018 itself.OnePlus 6T, on the other hand, was launched with Android Pie out-of-the-box.