Is there a way to add a product availability filter to a product page itself?

[mh3]

We are using the Search and Discovery app at the moment, but it only adds a filter to the collections page/product grid itself. We are looking to add a filter to the product page to allow a customer to see ALL of our variants, but have the choice to filter on our of stock or in stock items on the product. 

Open to theme changes, but not costly apps.