FetchApp is designed for the delivery of digital products, but you can sell physical products in your shop while still delivering digital products with FetchApp. After you import your products into FetchApp and attach files to them, you'll be able to "purge" your products that do not have attachments. So while your eCommerce system like Shopify, BigCommerce, or WooCommerce will contain both digital and physical products, FetchApp will only contain your digital products. 

To perform a product purge, go to "Products" > "Purge Products" within your FetchApp admin.