It wasn't too long ago that we saw OnePlus get into a huge controversy for prematurely killing their 2015 flagship, the OnePlus 2, by not following up on their update promises. Back then, they promised an update to Android Nougat for the OnePlus 2, which launched with Android Lollipop and was later updated to Android Marshmallow. This update was, however, only released for its successors, the OnePlus 3 and the OnePlus 3T, while the OnePlus 2 was left in the dark, with no possibility of an official update despite reiterated promises. OnePlus has greatly corrected this behavior since then, though. Not only have they released a full 2 updates for the OnePlus 3/3T (Android Nougat and Android Oreo), but a third one, based on Android Pie, has also been promised and now seems to be coming sooner than later.
OnePlus 3 XDA Forum OnePlus 3T XDA Forum
Following up with these promises, OnePlus recently started looking for testers to try out a closed Android Pie beta for the OnePlus 3/3T, indicating that the update will be coming eventually. Now, a new OxygenOS beta for the OnePlus 3 and the OnePlus 3T, based on OxygenOS 9 (Android Pie), has been released following up with this closed beta (and a public beta in China). There is a couple of things to keep in mind, however. First of all, these Android Pie builds are still not part of OnePlus' Open Beta program. OnePlus is calling this a "community beta," which will not be released via OTA, and will require users to manually install it. It is, still, the first publicly available official Android Pie build for both of these phones, since anyone can try it out as they want to.
Non-Pixel Android phones rarely get more than 2 major platform updates, and in the case of the OnePlus 3/3T, this will be the third one. So props to them for supporting their 2016 devices for so long.
This update also brings the latest April 2019 security patches, but given that it's not a part of OnePlus' usual beta program, there might be bugs or stability issues to handle. Still, if you want to bite the bullet, you can download and try out Android Pie now.
Download OxygenOS 9 for the OnePlus 3 Download OxygenOS 9 for the OnePlus 3T