It is not possible to limit gift cards that can only be used on a specific product. This is partially because gift cards are considered currency and in many areas this means they must be valid on any purchase from the merchant in question.

There is a workaround, however:

  • If you want to sell gift cards that are advertised as only being valid on a specific product, you could create a variant that has the exact price of the item. You can give it a name and link media to it, as permitted by your theme.
  • You can also create multiple gift card product pages for each product "specific" gift card; just be sure to add the provided code snippet or change to the provided product template.
  • The important thing to keep in mind is that there is nothing that would restrict the user from using the gift card on another product, although many store owners have success with simply marketing it that way.
  • Gift cards are always redeemed for the face value, so the redemption will still make it into your system as normal. 
  • If you charge shipping, you may want to make the gift card denomination match the product cost plus normal shipping fees.

For example:

  • A customer buys a gift card for Product A that's exactly $14.99. The customer pays $14.99 (less any discounts you offer). The gift card has a value of $14.99.
  • The recipient would, in most cases, go to your site and buy Product A and pay for it. In this example, if you have free shipping, the card would cover the entire purchase. If there is a shipping fee, the recipient would have to pay the shipping cost using another payment method.
  • If, for some reason, the recipient buys Product B for $9.99, the sale would go through as normal and the gift card would have a $5 balance. 
  • By extension, if the recipient buys Product C for $17.99, the gift card balance would cover the first $14.99 and the customer would have to pay another $3 to make up the difference.

In short, you can create the appearance that gift cards are limited to specific products, but Shopify won't automatically enforce this rule. 

Keep in mind, however, that you are still getting the sale and, in most cases, the number of cases of someone buying something else with a gift card are likely to be low.