[aaronmdjones]

> And it is unclear to me what value is added by the yubikey? And would any FIDO device work, or is this yubikey brand only?

As my sibling comment says, this doesn't use FIDO, it uses PIV. The YubiKey pretends to be a USB CCID-class smartcard reader [1], with a PIV-capable smartcard inserted. You could use any other PIV-capable smartcard, but then you would also probably have to buy a smartcard reader. I do have a Dell keyboard with a built-in smartcard reader [2], but I don't use it. This would also be much bulkier.

Edit: Smartcard vendors also vary wildly in terms of their support for "Things that aren't Microsoft Windows".

[1] among other things, such as a USB HID keyboard for the OTP functionality

[2] https://m.media-amazon.com/images/I/51m7Fuu3nWL.jpg