functions.php

/**
 * Breadcrumb na single de produto
 */
add_action( 'woocommerce_single_product_summary', 'single_product_breadcrumb', 0 );
function single_product_breadcrumb() {
	global $post;

	$out  = '<div class="breadcrumbs">';
	$out .= '<div class="breadcrumbs__container container">';
	$out .= '<a href="' . get_site_url() . '">Home</a> » ';

	$term_list = wp_get_post_terms($post->ID, 'product_cat', ['fields' => 'all', 'parent' => 0]);
	$primary_term = $term_list[0];

	if (isset($primary_term)) {
		$out .= '<a href="' . get_term_link($primary_term, 'product_cat') . '">' . $primary_term->name . '</a>';
	}

	$out .= '</div>';
	$out .= '</div>';

	echo $out;
}