I have only dabbled with ReScript so far and one of my first attempts was trying to extend the props of a react component. Firstly, by the approach that you plan to cover, i.e. spreading the existing props and adding custom props to a component. Secondly, by extending JsxDOM.domProps itself, e.g. to add popover and popovertarget. If not too out of scope, covering the latter might be a nice addition.
Looking forward to seeing the video 