When a customer pre-orders a product with pre-order purchase options attached, the resulting Shopify order will have an ‘on hold’ fulfilment status. This means the pre-order line item(s) will be ignored by ERP/fulfilment services until it’s released.
Then when the store is ready to charge, they can trigger the deferred charge, and if the payment is successful, the fulfilment hold will be released and the status will change to ‘unfulfilled’. (100% charge-upfront pre-orders can release fulfilment holds directly)
If the customer has a mixed order of some pre-order line items and some buy now line items, the former will be set to “on hold” and the latter set to “unfulfilled”.