Can you add an option to display the business registration number on the badge?

The badge modal (when a visitor clicks the badge) does show the registration number already — along with the registry body and the hash. The badge widget itself (the compact version that shows on your website) shows name and tier only to keep it compact. We could add a data-show-registration='true' attribute to show it in the compact view — logging this as a feature request. The underlying data is already there.