In Shopware 6, the visibility of products can already be controlled via rules by using the dynamic access extension (up to a certain point, as the stock is not being validated). However, there currently is no native way to hide or disable the “Buy / Add to cart” button based on rules, especially when combining customer groups with product stock conditions.

In B2B and hybrid B2C/B2B scenarios, it is common that products with stock = 0 (with closeout enabled) should still be orderable for specific customer groups, while the buy button should be hidden or disabled for all other customer groups. Moreover it should be possible to set "closeout" on sales channel level.