Have the contents of an external HTML file display on product page

My store’s products have a lot of technical data, most of which is shared among all the products within a category. I would like to be able to store this data in HTML files for each of the products and have it display on the product page.
The way I see it working is by placing a line of code in the product template that tells shopify to look for and display the contents of the file. I assume there needs to be naming convention for the file, for example product_id.htm, or whatever unique identifier Shopify would need to match up the correct file to the product. Then when the product page is compiled, this information would appear in place of the code.

Alternatively, if there is a way to put the name of the HTML file in one of each product’s field and have it display. Obviously, this option would require more initial work on our end, but if it will work, it’s OK!

I would greatly appreciate help with how this can be done. Thanks!