Rehub theme is the hybrid theme. It means it’s a Classic theme with some functionality from FSE themes. One of these functionalities is the option to create custom FSE templates and template parts for products.
If you are interested in how to add custom code areas and template parts inside Product page, check our documentation about code areas in product
You can also create 100% custom product template in Gutenberg. For this, create a New reusable template and select it as a Product Single page in template section
Everything which you place inside Content will be used as product template. You can use any Gutenberg addon for Woocommerce with dynamic blocks, but we recommend Greenshift Woocommerce addon because it has a ready pattern for Rehub.
Here is how to use it.