> Whether a PIN is used is determined by the RP on a per-authentication basis

Ahem, cough...

    ykman fido config toggle-always-uv

Does that work for Yubikeys other than the Yubikey Bio?

I just tried it on a 5C NFC (firmware 5.4.3) and got:

    ERROR: Always Require UV is not supported on this YubiKey.

So I'm really not sure this is an option for non-Bio keys, unless it was introduced quite recently.