@d4f2 had to remove your reply because one of the cited sources is notoriously unreliable and more likely to mislead than assist someone who's looking to see what's compatible with GrapheneOS and what's not.
@Hansel If you're looking for banking apps specifically, take a look at this list:
This is a community maintained list of apps that have been reported working. An app not being on that list doesn't make it incompatible with GrapheneOS. It just means someone hasn't added it yet. Realistically, the only reason why a banking app wouldn't work is if it requires a Google certified OS, and in my experience, most don't.
For general app compatibility, you really don't have to worry about it. GrapheneOS has great app compatibility thanks to Sandboxed Google Play.
If you have any specific apps you'd like to confirm, you can leave their names here and someone can try them and see if they work on their end.