For context, we have a Shopify application that provides merchants with an alternative shipping method and we recently released a feature where merchants have the option to have their Shopify orders be automatically marked as Fulfilled once they have created a shipment with us.
From what I have been told, the automatic fulfillment through the API is only possible if the product inventory is available (i.e. not zero). Is this true?
If not, is there a possibility that orders can be automatically marked as Fulfilled if product inventory does not exist? For example, if the merchant does not use Shopify to track inventory for their products.