In most of the cases either GrapheneOS + sandboxed Play Services or CalyxOS + MicroG works just fine with banking apps or any other apps.
What's not working: apps using strict SafetyNet checks, in-app purchases (on MicroG), GPlay license checks (on MicroG). And rest assured, location services will be a real pain in your ass on Graphene (and sometimes DejaVu may deadlock on Calyx, better turn it off completely and replace with "GSM Location" Unified NLP backend).
What's not working: apps using strict SafetyNet checks, in-app purchases (on MicroG), GPlay license checks (on MicroG). And rest assured, location services will be a real pain in your ass on Graphene (and sometimes DejaVu may deadlock on Calyx, better turn it off completely and replace with "GSM Location" Unified NLP backend).