Products can be marked with different visibility options within the admin dashboard:

Currently, the Product Query block doesn't respect this setting, and just shows every product.

By default, the Product Query block should respect the visibility options in both FSE templates and other editor context. That means that if a product is set to be “Hidden”, it should not show up even in Product Query blocks used in Posts and Pages. Eventually (issue link TBD) we'll add an option to override this within the inspector, but we'll settle for this default for now.