Aha, it’s not something you can access from the UI 
you need to use a “deep link” with a Pot ID obtained from the Monzo API 
It’s not easily accessible for the masses yet 
The good news is that Monzo have this new UI hidden behind a feature flag 
So it could appear for anybody at any time (assuming there’s no show stopping bugs)
Advanced Section
The format, if anybody is interested 
is:
monzo://pot_detail/{pot_id}
(where {pot_id} is obtained from Monzo’s API)