While this would be helpful, I’d find something a little like Curve to be more useful. Let me explain…
Imagine you have a Monzo account and two pots. Each pot has its own account number. Using the app, you can determine which account number payments or withdrawals come from (either by default or by next transaction).
Now let’s scale this to open banking and viewing other accounts through the Monzo app. Let’s say I have a Barclays savings account, linked to Monzo. I select this Barclays account as the one for the next transaction and hey presto, my Monzo card is used to authorise a Barclays transaction…
A bit like Curve in terms of the user journey, maybe, but possibly a whole lot more useful.