You can embed as many Shopify products as you like into an Exposure story using the "Embed" group type, and the Shopify Buy Button embed.
Generate a Shopify Buy Button embed code for your product. You can learn how to do that here.
Once you have the code, open your Exposure story, and click "Embed" from the group options.
Click "Embed your own code" from the Embed option tabs.
Paste your Shopify Buy Button code in full into the code area and click "Embed Content".
Click "Preview" and see how your product looks, and start selling.