Register Advanced Custom Fields for WooCommerce with the WordPress API

functions.php

<?php

/*
 * Register ACF fields to WordPress API
 * Tutorial: https://battlestardigital.com/wp-admin/post.php?post=2838&action=edit
 */

add_action( 'rest_api_init', 'bsd_register_acf_with_api' );
function bsd_register_acf_with_api() {
  if (!function_exists('get_fields')) return;

  register_rest_field(
    'product',
    'acf',
    array(
      'get_callback' => 'bsd_add_acf_fields',
    )
  );
}

function bsd_add_acf_fields( $object, $field_name, $request ) {
  $acf = get_fields( $object['id'] );
  return $acf;
}