Integrating Curve-like functionality inside bunq sounds indeed interesting. If bunq can at some point implement changing accounts for a transactions post factum, even better. So you always use the same card and you can later choose the money source. But, I also see where the difficulties with this are.
Edit: Not sure if I would feel "less shady" when using a card without any information on it, though, haha. That sounds very cool but would definitely confuse people.