https://developer-docs.amazon.com/sp-api/changelog/update-vendor-direct-fulfillment-orders-api-v2021-12-28-now-includes-hascustomizableitems
Update: Vendor Direct Fulfillment Orders API v2021-12-28 now includes hasCustomizableItems
The getOrder and getOrders operations now return the hasCustomizableItems attribute. You can use this attribute to determine if an order has customizable items.
direct fulfillmentorders api