If you want to integrate your existing blog posts, news, and topics to products, here is the product content relationship plugin.
Product content relationship plugin allows the store owner to manage which blog post, news or topic should be related to the specific product. With this plugin, you can choose between multiple widget zones which change the display zone of products in a blog post, news or topic pages and vice versa. Also, you can customize the number of products to be displayed in the related content entity page and the number of related content entities to be displayed on the product page.