Since Shopify does not support parent-child relationships for product categories (collections), they will be migrated and arranged in a flat structure. However, our migration tool preserves category hierarchy by transferring it into Shopify’s navigation system. By default, the migration tool will create a menu called “Migration Menu” to store the category hierarchy for you to display it on your storefront.
Additionally, you can manually create multi-level menus for collections and display them on your Shopify store by following this guide.