With the upcoming picu Pro 2.3.0 release clients will see an order status notification above their collection.
Order pending:

Completed order, which also contains a link to the invoice:

The invoices functionality can be disabled.
Failed order:

We also added the possibility for the client to return to checkout and place the order again. The client could also choose a different payment method, e.g. if their first choice didn’t work for them.
We also added a new filter picu_pro_order_status_notification, so the status message can be completely customized:
add_filter( 'picu_pro_order_status_notification', function( $message, $order_id ) {
$status = get_post_status( $order_id );
if ( $status === 'pending' ) {
$message = '<span class="order-status__message">We are still waiting for you the send over the money!</span>';
}
return $message;
}, 10, 2 );
