Emit events during setPreloader and subscribe to them from outside with JS

Hello, I’m working on a react app, which holds the iframe of the verge3d model in a ref (useRef hook)

I access the procedures defined in Puzzles this way:

const procedures = iFrame.current.contentWindow.v3d.puzzles.procedures;

I would like to dispatch events in setup preloader puzzle, so I could subscribe the react app components and show a loading view while the model loads. I do not wish to modify elements from parent doc inside puzzles, I would like communication to be from the react app to the iframe. How can I achieve this?