

Banking apps are highly variable, many work, many don’t. I have also heard that there are some required 2FA apps used some some European banks that currently don’t work. I don’t use any of these, so it hasn’t been an issue, but I just wanted to make sure the OP knew to be on the lookout.
Even if I could use one in the US on my carrier (I can’t), I’d probably not buy one because of the lack of headphone jack.