Nick here from Shopify. Great question!
Often when an order is in Pending Fulfillment for Oberlo, it is often that the product has not been purchased from the supplier/ seller yet. Would you be able to go into your Oberlo profile and double check this, please? If you have not yet purchased the products you can do so by selecting the orange order product button to buy the product from the seller. Something to remember is that Oberlo does not buy the products for store owners automatically nor fulfill them, these are things you would need to do yourself.
Looking forward to hearing from you to see if this is indeed the case, it is generally the most common thing to happens when it says Pending Fulfillment. If this is not what's happened, your best bet would be to reach out to the Oberlo support team directly about it here.
All the best, Nick
Ah ok, without seeing the order more closely or directly, it's difficult to troubleshoot and figure out what exactly is going on here.
Would you be able to reach out to the Oberlo team directly from the link here (there is a chat icon in the bottom right corner) or you can reach out to the Shopify support team about this here. Once you reach out to a support team and verify someone can take a closer look into why this might be happening for you and get it sorted so the fulfillment can move out of pending status.