How to disable the add to cart button if the shop owner does not have the premium role?
Yes, you can do this in twig file. So you will have to create a commerce product twig file(you can copy it from commerce module template). In the preprocess hook you will have to pass a value whether that product can show cart button or not. In your twig file you can use value of that flag around {{ product.variation }}. Add to cart button is rendered by this variable.