[grokx]

Right, most probably closed-source just like Android wear. Even manufacturers may not have access to the source code, they would just put their stuff in the vendor partition.

A good friend of mine works for a manufacturer that make watches running on Android Wear, and closed-source system updates pushed by Google turn OS-level regressions (like battery consumption issues) into nightmares. So they are switching back to their own AOSP-based OS.