On the product list we need to have a custom product attribute show and be selected before the user can add to cart. We have this work fine on the product detail page but cant find a plugin or example for the product list page. For example if we have a T shirt comes in s,m,l. the size is our custom attribute the price is s=$5 m=$10 l=$15. on the product list page we want a drop down that says size which then user pics size. It updates price and then allows user to add to cart. I would think this would be a very common feature but no luck finding a ready plugin or examples how to do this.
I think you have to take look at this tutorial
This looks like it would be a solution but its for magento 1.x and we are dealing with magento 2 a completely different animal.