Hey Christoph,
it is a really nice idea, I'm sure it will get lots of π !
You could check out such a page when you're not sure if a service is having hiccups just for you or for everyone.
Happy to hear you like the way we keep our users posted via notifications, Twitter and Together posts when something affects our services π
Also, be aware that you can already monitor iDeal π here: https://availability.ideal.nl/History?bank=bunq
Cheers!
Jan