Well, there is Sailfish Secrets.
https://sailfishos.org/wiki/Secrets_and_Crypto
I have no idea how secure the storage for it is though, but if you can evaluate that, it would be great.
To me the bigger hurdle to do anything PSD2-compliant is that it is designed for corporations, and all the FUD around liability that it brings.
I tried to get access to my own bank data through the mandated open API, but unless i’m a corporation, with proper accreditation at that, and a business plan that the bank has to approve, i am not allowed to. And they are fully within their right to require this according to PSD2. …and they want to be able to sue me into the ground at the drop of a hat if anything happens.
If you have a solution to that part, that would be quite cool. I just don’t see what entity could reasonably do this (and still care).
Prompted by this thread i actually started writing on a Citizens Initiative to ask the EU to mandate open options for accessing essential online services (banking/payments, government services). For example when adapting PSD2 to local regulation, the member states would also have to require the issuing banks to provide or otherwise enable platform independent means of identification for online purchases.
I’ll try to put it up somewhere when it has started taking shape, to gather feedback. By now i have seen this crap in too many disguises, so my collection of arguments has become pretty substantial. Anyone reading this: feel free to reach out to me for discussing or helping out, or just giving me a well-needed kick in the rear when i still haven’t published anything in a couple of weeks.