It would be incredibly tacky - and would probably break after a few uses unless Monzo pay more for stronger metal cards. Either way, I hope they don’t pass any of the cost of designing or making these on to normal users as it’s a complete waste IMO
It’s really not a useful thing when you think about it. How many times in the last year have you been in a position where you needed a bottle opener and didn’t have one available? As an example, I have a belt buckle that’s also a bottle opener - I‘ve worn it most days for years. I think I may have used it to open a bottle twice.
Not to mention almost definitely would increase the cost per card and reduce their durability (leading to more increased costs as cards need to be replaced more frequently).