LineageOS is great even without root, but I still recommend using Magisk on it for system-wide ad blocking (via e.g. AdAway) if nothing else.
A banking app may have a simple root check, or a SafetyNet check. You can use shamiko and safetynet-fix respectively to fool these, both have already been linked.
The are ways to make almost all banking apps work on a rooted, even de-googled, phone. See here: https://lemmy.world/post/683341