OnePlus 9 and 9 Pro can upgrade to Android 13 thanks to their new OxygenOS Open Beta program
OnePlus has finally moved its 10 Pro flagship out of its Open Beta phase of OxygenOS 13 (or OOS 13) development, leaving its predecessors to take its place. Those who own the 9 or 9 Pro can become testers for this updated software rather than run their current build of OOS based on Android 12.
As with all public beta builds, there is the risk of many more bugs and general instability compared to a 'normal' software version.
In addition, there are some known bugs thus far, which includes a loss of compatibility with the Verizon network; the inability to turn the phone's flashlight off from the lockscreen and its inability to store missed calls, but only if they came over VoLTE from iPhones.