My name is Lilith, I'm on the Social Care team at Shopify. Happy to help with this.
The editing tool for structured data management isn't a built-in quick-access feature on the admin at the moment. That said, I would love to send this to the team as a feature request for a future update. The more requests we get for a feature the higher up the queue it goes.
Although the feature isn't there at the moment, there are still several different methods to modify this. I've outlined a few below to help you out.
You can use a mix of HTML and Liquid in your theme code to insert rich snippets using JSON-LD. This will take some effort to set up, but once you have that set you'll have an easier time adding snippets in the code. This means that dynamic data will be pulled into the snipper rather than having to create multiple templates for each and every page of your site.
There are several apps in the app store that can help you out with structured data. Below I've listed the 3 that I've used or other merchants have recommended to each other.
Depending on your level of experience, if you're not 100% comfortable doing the above methods, we have an Experts Marketplace that's part of our ecosystem to help merchants with more customized needs.
You can jump into the marketplace to browse services and Expert level partners or request a quote by following this guide here.
I recommend using one method only and if you choose to use apps, make sure to only use one app. The simpler you can manage this in the above methods the better for your SEO.
Don't forget to use Google's structured data testing tool once you have made modifications.
Let me know how you do with the information above! I'm happy to answer any questions you think of as you work on your business.