Opening up the hardware on Apple Watch is a big step for the next generation of smartwatches.
Still so limited in what developers can access - they need to open it more - but I also recognize it is likely limited in the way it is because of concerns about battery life.
Battery life and also the fact that the current iteration of the Watch is still fairly limited in hardware components. That's what happens when you make a device that is intended to be the companion to a different device.