Custom Notifications

It’s possible with custom coding. You’d need to send the extra data to the WC_Pushover::send_notification() method and then add it to the $message.

https://github.com/growdev/pushover-for-woocommerce/blob/master/classes/class-wc-pushover.php#L263

You can use the WC_Order in notify_new_order() to get the extra information.