Got a new phone and holy fuck ever since Passkeys became a thing Apple's sign in for accounts is a clusterfuck of bad user experience.
For anyonee not familiar, when you activate a new phone from backup you will have to reauthenticate with the various email accounts you've setup. Cool easy right. Except my Office 365 is FIDO2 with a Yubikey. No problem those are supported on iOS right? Sure, except because Passkeys are a thing the OS wants to take over that function. Here was the sign in flow it ran me through.
1. Tap to reauth.
2. Mini browser opens for the Microsoft login which recognizes I've chosen FIDO2 as my primary sign in method.
3. iOS sees the FIDO2 request and presents a system dialog. Use a passkey or an external key? Well clearly an external key. *tap*
4. Get redirected to iOS keychain/passwords screen for no apparent reason. There's nothing there for me to do, since it's also in settings it wipes out the above process. Please return to step 1.
Literally couldn't use my FIDO2 key because Apple can't figure out how to handle external hardware based keys anymore apparently and insists on trying to pass you through to a software based key (Keychain, 1Password, etc)