Seems they are quietly working in the background:
She was behind the scenes at Monzo for a year before being appointed as CEO, having joined as a director nominee and licence advisor. Nelson is now tasked with getting Monzo its US bank licence, hiring the US C-suite and designing the actual product that it will take into the US market.
And regarding the timeframe for a US banking licence:
The launch itself is still a while off. Monzo has effectively said it will stay in beta and build up its waiting list until it can get a full licence (which could take until 2023). As a result, it’s essentially spent most of the last two years quizzing local customers what they want.