What’s your prefer two-factor authentication app for iOS? I'm looking for an app that offers the best combination of platform compatibility (preferably available on Mac OS, iPad OS, and iOS), security, usability, and reliability. It would be great if the app is open source and has a backup feature as well. [I came across a recent Wirecutter article from The New York Times](https://www.nytimes.com/wirecutter/reviews/best-two-factor-authentication-app/)that recommends Cisco DUO Mobile as the top choice, followed by Authy and Google Authenticator. I would greatly appreciate your insights and security perspectives. Thank you!