It'd be cool if payment cards had a built-in LCD screen for the PIN as a TOTP. That shouldn't be much harder for consumers than the existing card verification/security code.
Could be used for both - online purchases and bank logins.
Bear in mind these card readers were introduced in the UK and Sweden in 2007, around the same time as the first iPhone.
Most budget Android phones don't, and the iPhone one is locked down.
Some banks now have an in-app token.
Many bank apps also have some form of jailbreak/root detection. If the detection is tripped, the app will either kill itself, or disable the in-app token.
Also iPhones can now read NFC card. My partner already used her passport to get onto SmartId system in Lithuania.
In-app tokens rely on your phone - loose it and you are really screwed. Wanna let your accountant to use account while you on vacation - you can’t. Plus setup (or suspicious logins) normally depends on a SMS 2FA.