Breadcrumbs with BreadcrumbList schema

<?php
/**
 * Breadcrumb trail + BreadcrumbList JSON-LD.
 *
 * @package Acme_Theme
 */

defined( 'ABSPATH' ) || exit;

/** @return array<int, array{label: string, url: string}> */
function acme_breadcrumb_trail(): array {
	$trail = array( array( 'label' => __( 'Home', 'acme-theme' ), 'url' => home_url( '/' ) ) );

	if ( is_singular() && ! is_front_page() ) {
		$post = get_queried_object();
		if ( 'post' === $post->post_type ) {
			$cats = get_the_category( $post->ID );
			if ( $cats ) {
				$trail[] = array( 'label' => $cats[0]->name, 'url' => get_category_link( $cats[0] ) );
			}
		}
		foreach ( array_reverse( get_post_ancestors( $post ) ) as $parent_id ) {
			$trail[] = array( 'label' => get_the_title( $parent_id ), 'url' => get_permalink( $parent_id ) );
		}
		$trail[] = array( 'label' => get_the_title( $post ), 'url' => get_permalink( $post ) );
	} elseif ( is_category() || is_tag() || is_tax() ) {
		$term    = get_queried_object();
		$trail[] = array( 'label' => $term->name, 'url' => get_term_link( $term ) );
	} elseif ( is_search() ) {
		/* translators: %s: search query */
		$trail[] = array( 'label' => sprintf( __( 'Search: %s', 'acme-theme' ), get_search_query() ), 'url' => get_search_link() );
	} elseif ( is_404() ) {
		$trail[] = array( 'label' => __( 'Not found', 'acme-theme' ), 'url' => home_url( add_query_arg( null, null ) ) );
	}
	return $trail;
}

function acme_breadcrumbs(): void {
	$trail = acme_breadcrumb_trail();
	if ( count( $trail ) < 2 ) {
		return;
	}
	$last = count( $trail ) - 1;

	echo '<nav class="acme-crumbs" aria-label="' . esc_attr__( 'Breadcrumb', 'acme-theme' ) . '"><ol>';
	foreach ( $trail as $i => $crumb ) {
		echo '<li>';
		if ( $i === $last ) {
			echo '<span aria-current="page">' . esc_html( $crumb['label'] ) . '</span>';
		} else {
			echo '<a href="' . esc_url( $crumb['url'] ) . '">' . esc_html( $crumb['label'] ) . '</a>';
		}
		echo '</li>';
	}
	echo '</ol></nav>';

	$items = array();
	foreach ( $trail as $i => $crumb ) {
		$items[] = array( '@type' => 'ListItem', 'position' => $i + 1, 'name' => wp_strip_all_tags( $crumb['label'] ), 'item' => $crumb['url'] );
	}
	printf(
		'<script type="application/ld+json">%s</script>',
		wp_json_encode( array( '@context' => 'https://schema.org', '@type' => 'BreadcrumbList', 'itemListElement' => $items ), JSON_UNESCAPED_SLASHES | JSON_HEX_TAG | JSON_HEX_AMP )
	);
}