Do note that many banking apps use google safetynet, which means they won't work on anything that deviates too much from normal android and it won't work on anbox.
I still haven't gotten anbox to work but I also realized every single app that I used besides Snapchat had a website that worked well (including my banking app.) Some banking apps apparently include a TOTP implementation, this is a trivial algorithm and there are many native Linux apps for it.