I absolutely love the near real-time’ness of the transaction notifications and it got me thinking that leveraging it might be useful in the use case of linked cards. e.g.
Family groups where one or more parents have issued cards to their children and the one or both parents receive a notification not just to view the transaction, but to catch it in-flight and accept or reject it.
You could set up rules around the notifications/authorisations like granting autonomy for individual transaction limits up to a certain value, aggregate daily limits, and then do the notification/authorisation when the transaction breached those limits.
I know your focus is on getting the fundamentals right at the moment, just thought this could be an interesting roadmap feature and potentially a USP.