I love the concept of Curve and have used it for lots of transactions now, over 7 different cards.
The only thing I dislike is that every time I use it, I have to get my phone out and login to the app to see which of my cards is selected and then probably change the selection.
I therefore suggest the following ideas in order of complexity:
1 - Make the selected card name and image visible in the app before login, just to speed up the process.
2 - I’ve seen a credit card that had a small e-ink display on it and a few buttons. (fuzecard) Surely this would be the perfect way for the Curve card to display which card is currently selected, as well as allowing you to change the selected card.
Number 2 is a big change for sure, but this would be an amazing leap forward that I for one would happily pay a premium for.