Display by Categories in search results

WP_Query class is typically used to query for products and any other post types. Oddly enough, WP_Query cannot accommodate ordering query results by taxonomy terms like categories. You could instead make two queries, one for products, then again for showroom items. How you’d accomplish this involves customizing the search results template used by WooCommerce. WooCommerce has their own dedicated support channels where support staff there are in the best position to advise on customizing WC templates.

A different approach would be to compose your own search SQL query that is capable of ordering by category. You can use the “posts_request” filter to replace the SQL that WP_Query came up with with your own SQL.