I am open for suggestions, but anything wanting to give a desktop like experience is going to be complex. Like the user clicks a button, now widget a1 » a1.3 » a1.3.2 » a1.3.2.2 should be in an "open state", while widget b1 » b1.2 » b1.2.1 needs to be in "disabled state" and widget c3 » c4 » c5 shows a status message.

Sure, and the further you go in that direction, the more you're building a traditional desktop GUI experience, which was always a bad fit for the web.

So yes, if that's really what you want to do, React or similar is probably what you want.

If.

I used to do things like that with about 10 lines of jQuery.

But we as a species decided that jQuery bad :(