The free YubiKey from Wired is a base model. It doesn't have NFC/Bluetooth etc. But if you get the latest model from this article's promoted model (YubiKey 5) it will have all the bells and whistles for mobile/USB-C/contactless and even supports PIV SmartCard protocol, where you can upload a key pair you generated on your own outside of YubiKey.[1]
[1]: https://www.yubico.com/wp-content/uploads/2018/09/yk5-diagra...