Changing the order summary

Checkouts, by default, display an order summary on specific steps. This summary is powered by a view which can be modified. This is the Checkout Order Summary (commerce_checkout_order_summary) view. Changing this view will change how the order is displayed in summary during checkout.

Checkout Order Summary view

Changing the view

There is no user interface for changing the view provided. The view is added by the CheckoutFlowBase class when building the checkout flow form:

if ($this->hasSidebar($step_id)) {
  $form['sidebar']['order_summary'] = [
    '#type' => 'view',
    '#name' => 'commerce_checkout_order_summary',
    '#display_id' => 'default',
    '#arguments' => [$this->order->id()],
    '#embed' => TRUE,
  ];
}

To use a completely different view, you will need to use hook_form_alter to change the view name, or a provide a custom checkout flow plugin.