Now that Pro Forms will become nestable i thought about a neat use case.
Create an Ajax Search Form Field.
You can bind it to search inside whatever Post Type you want.
Options to search also Custom Fields for that Post Types.
Integrate it with Relevanssi search plugin or SearchWP.
Below that search field you build the nestable checkboxes like you show us in this post
The main difference would be that, instead of defining what Query Loop the nestable checkboxes should bind to, now with live ajax search field, you will populate these nestable checkboxes on the fly.
You have Woocommerce with thousands of products.
Create an enquire form that users can search for products having X attribute, check what products they want and send the enquire form.
Side note. The container should have a scrolling option if many products are returned.