My name is Rae, and I work for Shopify.
The Shopify App Store has a few different apps that can be used to create a registry on your site. Some of the options I recommend looking over are:
It's important to mention though, that each of these apps are developed and supported by third-party companies. So, if you decide to use one of these options, and have further questions about how the apps work, or the charges associated with using the apps, please reach out to the app developers directly.
In the meantime though, if you're looking for any specific features in a gift registry that these apps don't offer, please feel free to tell me a bit more about your specific needs, and I'll be happy to look for some alternatives that might suit your business better.
I look forward to hearing back from you about this!