I've been looking for a device, smartcard or USB that does two things:
provide storage to a private digital signature key (used with in a standard x509 certificate) for signing documents
provide U2F credentials for authentication with web applications.
optional: NFC or a way to use it from mobile device
I've found only one vague reference that a yubikey could do both (but it's not fips140-2 certified). Why are the other players in the field not developing devices with both functionalities? Gemalto, nitrokey, etc.
Is there some fundamental incompatibility with "old" PKI smartcards and U2F ? Both do similar operations at their core.