Вывести подкатегории в списке каталога WooCommerce

Если нет в шаблоне файла woocommerce/archive-product.php, то копируем его туда из /wp-content/plugins/woocommerce/templates/archive-product.php

Открываем файл на редактирование и добавляем woocommerce_product_subcategories()

Пример добавленной функции в оригинал от WooCommerce 5.4.1:

<?php
/**
 * The Template for displaying product archives, including the main shop page which is a post type archive
 *
 * This template can be overridden by copying it to yourtheme/woocommerce/archive-product.php.
 *
 * HOWEVER, on occasion WooCommerce will need to update template files and you
 * (the theme developer) will need to copy the new files to your theme to
 * maintain compatibility. We try to do this as little as possible, but it does
 * happen. When this occurs the version of the template file will be bumped and
 * the readme will list any important changes.
 *
 * @see https://docs.woocommerce.com/document/template-structure/
 * @package WooCommerce\Templates
 * @version 3.4.0
 */

defined( 'ABSPATH' ) || exit;

get_header( 'shop' );

/**
 * Hook: woocommerce_before_main_content.
 *
 * @hooked woocommerce_output_content_wrapper - 10 (outputs opening divs for the content)
 * @hooked woocommerce_breadcrumb - 20
 * @hooked WC_Structured_Data::generate_website_data() - 30
 */
do_action( 'woocommerce_before_main_content' );

?>
<header class="woocommerce-products-header">
	<?php if ( apply_filters( 'woocommerce_show_page_title', true ) ) : ?>
		<h1 class="woocommerce-products-header__title page-title"><?php woocommerce_page_title(); ?></h1>
	<?php endif; ?>

	<?php
	/**
	 * Hook: woocommerce_archive_description.
	 *
	 * @hooked woocommerce_taxonomy_archive_description - 10
	 * @hooked woocommerce_product_archive_description - 10
	 */
	do_action( 'woocommerce_archive_description' );
	?>
</header>
<?php
if ( woocommerce_product_loop() ) {

	/**
	 * Hook: woocommerce_before_shop_loop.
	 *
	 * @hooked woocommerce_output_all_notices - 10
	 * @hooked woocommerce_result_count - 20
	 * @hooked woocommerce_catalog_ordering - 30
	 */
	do_action( 'woocommerce_before_shop_loop' );

	woocommerce_product_loop_start();
	
	woocommerce_product_subcategories();

	if ( wc_get_loop_prop( 'total' ) ) {
		while ( have_posts() ) {
			the_post();

			/**
			 * Hook: woocommerce_shop_loop.
			 */
			do_action( 'woocommerce_shop_loop' );

			wc_get_template_part( 'content', 'product' );
		}
	}

	woocommerce_product_loop_end();

	/**
	 * Hook: woocommerce_after_shop_loop.
	 *
	 * @hooked woocommerce_pagination - 10
	 */
	do_action( 'woocommerce_after_shop_loop' );
} else {
	/**
	 * Hook: woocommerce_no_products_found.
	 *
	 * @hooked wc_no_products_found - 10
	 */
	do_action( 'woocommerce_no_products_found' );
}

/**
 * Hook: woocommerce_after_main_content.
 *
 * @hooked woocommerce_output_content_wrapper_end - 10 (outputs closing divs for the content)
 */
do_action( 'woocommerce_after_main_content' );

/**
 * Hook: woocommerce_sidebar.
 *
 * @hooked woocommerce_get_sidebar - 10
 */
do_action( 'woocommerce_sidebar' );

get_footer( 'shop' );

В файл шаблона functions.php добавить обработку вывода:

function print_shop_product_subcategories($args = [])
{
	$parentid = get_queried_object_id();
	$args = [
		'parent' => $parentid
	];
	$terms = get_terms('product_cat', $args);
	if ($terms)
	{
	?>
		<ul class="product-cats">
		<?php foreach ($terms as $term) { ?>             
			<li class="category">                        
				<?php woocommerce_subcategory_thumbnail($term); ?>
				<h2><a href="<?php echo esc_url(get_term_link($term)); ?>'" class="cat-<?php echo $term->slug; ?>"><?php echo $term->name; ?></a></h2>
			</li>
		<?php } ?>
		</ul>
	<?php
	}
}
 
add_action('woocommerce_before_shop_loop', 'print_shop_product_subcategories', 50);