To wait 30 minutes to fulfill a gift card, you can use the Wait action in Shopify Flow, as described in the actions.json document. However, the exact implementation details are not provided in the available documents.
You can create a workflow that uses the Fulfillment order ready to fulfill trigger, as described in the triggers.json document, and then add a Wait action to delay the fulfillment of the gift card by 30 minutes.
Additionally, you can use a template such as Hold fulfillments based on total order value, as described in the templates.json document, as a starting point and modify it to fit your specific use case.
Please note that the available documents do not provide a straightforward answer to this question, and some experimentation with Shopify Flow may be required to achieve the desired outcome.