Magento 2 How to get product qty before added to cart with JS?

I’m trying to get the quantities of a bundle product before added to cart with js, jquery, knockout js
W or whatever can allow me to do this. I want to validate that user cannot add to cart if the qty of products added to bundle is not 7.

I show an example.

I need to get those qty and enable or disable Add to Cart button, depending on the qty.

Where can I start to have a look?
I know that in module-checkout/view/frontend/templates there are some useful templates that I can override.

Thanks!