Hi @verdantunripe,
To recap, it sounds like your end goal is to be able to add Builder sections that are unique to each product to your existing product pages. Is this correct? Are you using a 1.0 or 2.0 theme? With Builder, you have the ability to add custom sections to any existing page. Custom sections can be installed directly in your themes code, in your case the product page template file. You have full control of where the Builder section displays on your page. Once you’ve created your custom section and installed the Builder snippet in your theme, you could create multiple Builder sections for each product with product targeting so you can display unique content for each of your products. Let me know if this makes sense for what you’re trying to achieve!