I'm currently trying to set up 2FA full disk encryption using Yubikeys and LUKS. Having bought a blue Yubikey, and done a lot of reading and experimentation, I finally discover that the blue version only supports U2F, not OTP as required by yubikey-luks. It would have been good to know that before spending money. In theory the information was available in advance, but it really wasn't very easy to find.