Use highest & lowest product category slug in Products & Product categories default permalinks

highest-lowest.php

<?php

function pm_use_highest_level_slug_posts($replacement, $replacement_term, $post_object, $terms, $taxonomy, $native_uri) {
	if(!empty($post_object->post_type) && $post_object->post_type == 'product' && !empty($replacement_term->term_id) && !$native_uri) {
		$term_ancestors = (array) get_ancestors($replacement_term->term_id, $taxonomy);
		$top_ancestor_id = (!empty($term_ancestors)) ? end($term_ancestors) : false;

		if($top_ancestor_id) {
			$top_ancestor = get_term((int) $top_ancestor_id, $taxonomy);
			$replacement = "{$top_ancestor->slug}/{$replacement_term->slug}";
		}

	}
	return $replacement;
}
add_filter('permalink_manager_filter_term_slug', 'pm_use_highest_level_slug_posts', 9, 6);

function pm_use_highest_level_slug_terms($replacement, $replacement_term) {
	if(!empty($replacement_term->taxonomy) && $replacement_term->taxonomy == 'product_cat') {
		$term_ancestors = (array) get_ancestors($replacement_term->term_id, $replacement_term->taxonomy);
		$top_ancestor_id = (!empty($term_ancestors)) ? end($term_ancestors) : false;

		if($top_ancestor_id) {
			$top_ancestor = get_term((int) $top_ancestor_id, $taxonomy);
			$replacement = "{$top_ancestor->slug}/{$replacement_term->slug}";
		}

	}
	return $replacement;
}
add_filter('permalink_manager_filter_default_term_slug', 'pm_use_highest_level_slug_terms', 9, 2);