Update: As promised OnePlus has released Android P Beta for the OnePlus 6, soon after the announcement, and before it goes on sale next week. It also warns that some functions like VoLTE and Face Unlock doesn’t work. You can download Android P ROM from here and flash manually at your own risk. You can also easily roll back to Android Oreo by flashing the ROM here. Check out the source link below for flashing instructions. The company said that it will release device trees and kernel sources for the phone soon.