Currently, the Inbound Shipment Add-on flows work with the traditional Inbound Shipment Plan API, which will be deprecated soon (December 2024). This “legacy” API only supported Item Level Detail and the confirming of packing, dimensions, and labels would all be done in Seller Central, not via the integration.
Recently (March 2024) Amazon released updated APIs in the Selling Partner API to support submitting carton details and dimensions.The Celigo Product Team is working on this currently and we should have updates coming soon. I am hoping that the updated integration will cover carton contents and dimensions, but I will work on confirming that for you.