Have a look at the PostmarketOS device list. There are a ton of devices that boot, but the vast majority are missing critical features that render the device almost useless for anything but a server. The only android phones that I know of that run well with usable features and performance are the Oneplus 6/6T, Poco f1, Pixel 3a, shift6mq and fairphone, though even then there are crucial features missing. A modern phone built for Linux with a modern chipset, working camera, USB and sound would be awesome, but such a device does not exist AFAIK.
I’m pretty sure my bank’s android app is just webview considering it has a cookie banner when starting it and it looks almost identical to the actual bank website. The biggest feature of the bank app is for 2FA, but it’s not like it’s much more convenient than SMS and they really should be supporting FIDO2 and TOTP codes for actually secure 2FA.