My understanding of PSD2 is that it requires banking transactions to be "machine-readable" whatever that means. So there's an actual legal requirement for making data accessible outside of the browser.
The problem I faced when I looked at data export was that none of the banks had any apis. You always had to go through 3rd party commercial apis. Maybe there are ways bur I didnt find them
If you're talking about European banks they all have APIs. But only licensed companies can use them directly. Those companies are called AISPs within the PSD2 framework, sometimes referred to as aggregators. Some of them have ways for individuals to access their own accounts at banks via the AISP APIs. But there are limitations, one major one being that PSD2 doesn't cover credit card data or anything other than deposit accounts. [I'm a product manager at a bank]
