In essence, we are looking to implement a feature wherein a payment method is hidden upon the application of a gift card during the checkout process. We are exploring the feasibility of achieving this objective through the Payment Customization functionality available within the Shopify Functions API.
Your insights into whether this functionality is supported by the Shopify Functions API would be greatly appreciated. Additionally, if you have any suggestions or alternative approaches to accomplishing this use-case, we would welcome your input.
I made a similar solution for a client. They need to hide COD when gift card is applied. I used the app : https://apps.shopify.com/checkout-ninja . The customisation only work with Shopify Plus customers.