Absurdly precious in this case, given that it's just an RPC wrapper around the closed-source blob running on the GPU processor core which contains the real OpenGL ES driver. This reveals literally no technical details about the actual GPU hardware that the existing API didn't.
Having open drivers is further enhanced by the limited hardware models, it means more time to focus on getting the most out of the hardware instead of getting the stack to be compatible with different hardware all the time.
Hopefully this is the start of a trend.