It would be nice to have a feature to automatically maintain a minimum balance in the spending pot for day-to-day use e.g. £200, or whatever the user decides is best for their needs.
If a purchase brings the balance below the configured value then it would automatically transfer available funds from the main pot → spending pot to restore the minimum balance.
As an alternative, a much simpler improvement could be to notify the user via push notification whenever their spending pot balance drops below the configured minimum.
Currently when using the card I have to constantly monitor my balance to make sure I have enough and I think some of these improvements would reduce the manual effort and make it more enjoyable to use.