I've happily used LineageOS without gapps for years across several OnePlus devices. If I ever need a new phone I check their supported devices list to pick, and the stock ROM on my new device gets overwritten the day it arrives. Currently using a OnePlus 8T. When I move on from this device as my primary someday, I may put postmarketOS on it to extend its usefulness.
A large amount of work has been put into making Graphene specifically work with banking apps. Mine does, for instance.