No, not all Shopify apps work headless. Some may, and some may not. It’s the responsibility of headless agencies to make apps compatible with the headless store. You must clear terms and conditions while migrating from the traditional Shopify store to the headless store. Usually, the Shopify headless store may only support 50-60% of the existing applications. In such cases, the headless agency searches for similar apps compatible with your headless front end or develops custom apps to replicate the functionality.