Drupal Commerce: Add default CAPTCHA to checkout form step

Adding a captcha to a Drupal Commerce Checkout step isn't as simple as expected, as adding it via "Captcha points" shows the captcha on any Checkout step. So you need to add a little snippet in a custom module instead:

/**
 * Implements hook_form_FORM_ID_alter.
 */
function MY_MODULE_form_commerce_checkout_flow_dd_multistep_order_request_alter(&$form, \Drupal\Core\Form\FormStateInterface $form_state, $form_id) {
  // Add captcha to checkout form:
  if ($form['#step_id'] == 'order_information' && !\Drupal::currentUser()->hasPermission('skip CAPTCHA')) {
    $default_challenge = \Drupal::service('config.manager')
      ->getConfigFactory()
      ->get('captcha.settings')
      ->get('default_challenge');
    $form['captcha'] = [
      '#type' => 'captcha',
      '#captcha_type' => $default_challenge,
    ];
  }
}

Perhaps someone would like to take the time to implement this as a simple module with configuration options for the step and the captcha type? ;)