As far as I know a few iOS 9 features are supported in the beta. I'm still on iOS 8 - I could update, but I can't use all of the actually useful features (split screen, picture-in-picture, etc.) because Apple decided my iPad was too old. But hey, at least I could have lowercase letters on my keyboard!
Python 3 is unlikely to happen because of the major incompatibilities with Python 2. This would require a lot of work on omz's side, and most user code would break. It's also not possible to ship both Python 2 and 3 in a single app (or as an in-app purchase), because of Apple's restrictions on dynamic linking. There's a nice long thread about this topic somewhere on the forums, if you're interested in the exact details.