https://www.techradar.com/news/android-pie-beta-arrives-on-the-oneplus-6-heres-how-to-get-it

OnePlus has just launched its first open beta release of Android Pie for the OnePlus 6. Users having the phone will be among the first to experience Google’s latest OS.

For the first time ever other companies have partnered with Google to support the Android Beta Program. Google had announced the Android Pie update for a handful of handsets from select OEMs.