This is just so fantastic, I have been looking for something like this for the open-source edtech app builder Flow (https://github.com/opencurriculum/flow) for the past year! Talked to the WebStudio guy and did so much research, but nothing was just right. This feels JUST. RIGHT.
Btw, a very easy big win for you would be to port the side styles/interactions panel of WebStudio into this. And by port I mean extracting the code to make a common open-source library with the correct license and putting it in Puck.
Thank you for all the hardwork!