The ability to take the money in a pot and move it to a savings bank to earn interest, all without leaving the Monzo app. And to still see that money within the Monzo app as a “savings pot”. I opened a Shawbrook account through our marketplace, and it was ok, but I had to re-enter a lot of information that Monzo already. And now that money feels invisible. I’ve lost track of it.
Also, automated business-expenses submission. I have photos of receipts and tags, so this should be simple to automate. I wrote a (ranty) blog post about this a few years ago.