All those disclaimers are out there for liability purposes. It is highly unlikely that you will brick your phone as long as you follow the instructions and avoid making any modifications to the way the hardware runs (do not overclock, do not underclock etc).
That might be your bank. My bank is as annoying as you describe, but it is as secure as you’re saying it should be. 2FA, they hold up suspicious purchases to see if it’s really me, I can lock and unlock my cards from the app. Smaller banks tend to be the way to go, or credit unions if you have a good one nearby.