So, then, if Apple wanted to adopt a similar solution to Google - i.e. for their own enterprise security, as opposed to for their customers - could they use one of the Yubikey NFC options, or, would they have to ‘create’ a Bluetooth-specific device?
Maybe the long-rumoured Steve Jobs ring could take the form factor?!
And from an Apple customer perspective, is there a valid argument to be made that iOS devices can be, or are currently, less secure than Android counterparts because of the current lack of Yubikey / U2F options?
“Besides the fact that the NFC Reader interface can only be fired up from an app, Core NFC [in iOS 11] does not allow for write operations that are required for authentication protocols like FIDO U2F. ...
However, because NFC tag reading is supported, it allows developers to build apps, including consumer facing or purpose-built enterprise applications, with one-time passcode (OTP) support.”
Which is what ‘smiley1437’ and others have effectively stated in other parts of this thread.
edit: added last sentence
Apple limits the capabilities of Yubikeys so much that it's best to summarize it as "Doesn't work". It's more of Apple's anti-competitive restrictions that seem to go unnoticed by most people because they have a shiny UI.