A lot of older PC games can run just fine on modern phone hardware. I’d buy a SteamOS version of a phone that has some modular or built-in set of buttons and analog sticks. I don’t know how the app ecosystem would work for sensitive things like banking but it’s mostly a minor issue for me.
Mobile sucks. Smartphones are just too limited for real gaming. First problem is the hardware; you cant just put a desktop or laptop processors into a mobile device. Second is a small screen, which is very difficult to use for touchscreen controls and simply too small to actually see what is being displayed.