Access to that kind of data requires regulation, a lot of it and that's why Third Party Providers exist. There are a lot of them in Europe and they're not expensive.
I actually didn't expect to find anything about bunq around here but I have to say they're the worst bank I've worked with. When we started working with them, their API were broken and the devs had no idea why. It seems to have improved recently but it's definitely not a bank to praise for their API.