On an interesting note, that also means that the 2016 smartphones are getting the Android update ahead of the more recent OnePlus 5 and OnePlus 5T. OnePlus has been testing the Oreo update for it's 3 and 3T handsets since October in beta form but is now being made available as an official update finally.
The OxygenOS 5.0 comes embedded with features from the Android O (Oreo 8.0). OnePlus says it will deliver Android Oreo to the latest flagship in early 2018.
Android's latest OS update, Android 8.0 start releasing for the high-end non-Google smartphones.
OnePlus has finally announced the Android Oreo update for its a year ago flagship phones while the more recent OnePlus 5T continues to run Android Nougat. These include Parallel Apps, Picture in Picture, Auto-fill, Smart text selection, and a new Quick Settings design.
The Open Beta update released last month also came with the same changelog and included the same September security patch update. There hasn't been any significant leap in hardware over the past 6 months, so what the OnePlus 5 and OnePlus 5T both pack is pretty much still top-of-the-line - a Snapdragon 835 and 6 GB or 8 GB of RAM. Now, OnePlus has also confirmed that the Oreo update is now available for OnePlus 3 and OnePlus 3T smartphone. In addition to this, the OxygenOS 5.0 for the OnePlus 3 and 3T has added the ability to upload photos from the camera roll directly to Shot on One Plus. All the popular brands of the world have jumped leaps by introducing fully bezel less design and also removing the fingerprint sensor so as to make Face ID the common way to unlock a smartphone.
If you don't see any push notification on your phone's display after a couple of days, you can even check for the new updates manually. A broader rollout of Oreo update can be expected in a few days.