Hi,
The problem with extending an article as a product is that you will be limited by what Joomla articles can do.
For example, having several categories for an article. It's quite common to have a product in several categories and Joomla doesn't allows for that due to the way categories and articles are linked together.
That's why HikaShop has its own product entities and doesn't rely on articles. Instead, we offer the possibility to link products with aticles with this product tag system.
The Joomla search system can already search in the content of the articles, whether there is a link to a product or not.
And if you want to have the search gives you a link to the article thanks to a value entered in a custom product field of the product (I guess that it's the limitation you're talking about ?), that's still possible. For that, enter the link of the Joomla article in the canonical URL of the product and activate the HikaShop products search plugin and configure it to search on these fields. The search will then display product results based on their custom product fields and these results will poin to the Joomla article.