Hierarchical categories for the plugin WooCommerce Google Product feed

categories_with_childs.php

<?php

add_filter( 'woocommerce_gpf_elements_google', function ( $elements, $product_id, $variation_id ) {
	$elements['product_type'] = array_map( function ( $item ) {
		if ( empty( $item->parent ) ) {
			return $item->name;
		}
		$parent_list = array_reverse( get_ancestors( $item->term_id, 'product_cat', 'taxonomy' ) );
		$parent_list = array_map( function ( $term_id ) {
			$term = get_term( $term_id, 'product_cat' );
			if ( isset( $term->name ) ) {
				return $term->name;
			}
			return '';
		}, $parent_list );
		return implode( ' > ', $parent_list ) . ' > ' . $item->name;
	}, get_the_terms( $product_id, 'product_cat' ) );
	return $elements;
}, 10, 3 );