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.
I love larger displays. Easy on the eyes, better gaming and video experience. Still, on many newer phones aspect ratio is a problem for me. If the phone’s screen is something like 21:9 then it’s only really big on paper, since videos won’t fit perfectly, and the text and UI elements of games I play would still be pretty small, since they scale with the screen’s height in landscape mode.
The are ways to make almost all banking apps work on a rooted, even de-googled, phone. See here: https://lemmy.world/post/683341