I’m thinking of switching to a bank that uses its mobile app for 2fa. I use a dumbphone flipphone as my daily driver that only has talk and text and is not able to download apps. I do have an old smartphone that is going to stop receiving updates soon. I was wondering if it would be safe to use the mobile banking app for 2fa on the old phone after it stops receiving updates. I would plan on factory resetting the phone and not downloading or using any other app on it (including the browser). It would also have no Sim card in it. I would leave it off and only turn it on and use WiFi for using the banking app for 2fa purposes.
Well that sounds terribly inconvenient when you want to go anywhere and have to bring the second phone with you to log into your bank? Just sounds like an infuriating setup to me but if you’d like it I guess just go for it
Anyways convenience issues aside I think it would be fine.