Is AOSP the Open Source Version of Android?

AOSP is by definition, the open source version of Android. It's waiting until things become truly stable and adopted ecosystem-wide. For these things that are just happening or rapidly evolving, we have a bit of a side channel called extension house. They use the same methodology they're expressed in HIDL, but are not in AOSP. And so there's this aspect of being able to query what's available and then make a decision based on the available data every time you boot.