This is a very interesting take on "how can we test/poc a given component. I would be great to see a demo for a full application given this can help system designers build complex systems and track what activities are needed. Looking at the iPhone lock screen example [1], this is very useful. you can see that this is not aiming to do the UI render of the actual components, more about plugging in other resources like images.

[1] https://sketch.systems/tutorials/iphone-lock-screen/