It ain't your data, it's the bank's data about you. Banks are shitty about access, APIs because they are perpetually in CYA mode from KYC/AML rules from the US (also on most foreign banks) and GDPR and cousins in Europe.
I was actually surprised how many bank apps will work under GrapheneOS even if only partially.
"Power users" don't make them more money. In fact, from their POV, you're a legal, reputational, and security liability.
They often act as marketing and can find and report security vulnerabilities rather than the criminal element doing so first.
Hmmm then why are banks telling people to not use AI systems to log into their bank?
https://www.reuters.com/legal/government/us-banks-detect-una...
https://www.cbc.ca/news/business/canadian-banks-block-ai-9.7...