How to add non-visible products from the catalog to the quotation?

Create the product in your catalog, then set its visibility to “Nowhere” in the product options. It will no longer appear in catalog listings or native search.

Keep the product active and available for order: the module’s back-office product search uses these criteria.

In the quote, search for the product by name or reference and add it like another catalog product.

Warning: “Nowhere” hides the product from listings and search, but its product page remains accessible through its direct URL. This does not make the product private.