bookreader it doesn't seem to specify any particular implementation
I think (from memory) that for approving transactions you cannot have a generic 2FA code but you need to somehow reference the transfer amount and recipient.
So for example if you want to use online banking in the browser to send €125.00 to someone with an account no. ending in xxxx9876, you'd go to your app, go to "generate transaction code", enter something like 987612500, enter your password or fingerprint, then you get a 2FA code back that you enter in the online banking (and if you made a mistake when entering 987612500 your code from the app won't work). This is how it works for HSBC for example.
Some banks have made it a bit simpler and you basically just need to open your app where you get a pop-up saying: "Please approve online payment of £125.00 to xxxx9876, enter password/fingerprint".
But just normal TOTP is not enough, unfortunately.