Woodmart search form

Hello,
In the Woodmart search form (header search with category dropdown), I want to show only parent product categories (hide subcategories) and hide empty categories.
I tried using the following hooks, but none of them had any effect:
• woocommerce_product_categories_dropdown_args
• woodmart_get_categories_for_search
• woodmart_search_categories_list

It appears that the search dropdown loads categories from a custom template or an AJAX function that bypasses these filters.
Can you guide me on how to filter/override the category list for the search select? Or which hook/template should I modify safely?

Thank you!
Kind Regards
Erik