What kind of actions can gentoo do with your financial accounts, and what levels of user authentication does it use to do it? My phone can effectively act as a bank card with contactless payment or I can transfer up to a daily allowance (that would be painful to me if it was misused) of thousands with biometric auth. Similar to the OS if you're doing that with any browser with a web login you could potentially compile it to behave how you like or lie about what it's doing

Because it's a bank there's going to be insurance behind the scenes to cover them if something goes wrong, and I assume part of that is ticking off enough points to be confident a transaction is secure or different payment limits on confidence levels.