Add SKU to Product Name

/**
 * Create a workaround class for backward compatibility
 */
if ( ! function_exists( 'WPAS' ) ) {

    class WPAS_Workaround {
        public $products_sync;
    }

    function WPAS() {
        return new WPAS_Workaround();
    }

}

add_filter( 'wpas_hierarchical_taxonomy_dropdown_options_label', 'wpas_custom_product_label', 10, 3 );
/**
 * Add SKU after product name in the products dropdown
 *
 * @param string $label The option label
 * @param WP_Term $term The term object
 * @param mixed $value Option value if any set
 *
 * @return string
 */
function wpas_custom_product_label( $label, $term, $value ) {

    global $wpas_product_sync;

    if ( 'product' !== $term->taxonomy ) {
        return $label;
    }

    $is_sync = WPAS()->products_sync->is_synced_term( $term->term_id );

    if ( false === $is_sync ) {
        return $label;
    }

    $sku = get_post_meta( $is_sync, '_sku', true );
    $label = "$label - $sku";

    return $label;

}