I bought a YubiKey so I could use it on my laptop with LastPass. Works fine. One day I grabbed my iPad and opened the LastPass app and it hit me... how am I going to authenticate with a YubiKey on an iPad. It took my password and then just worked.

I guess I misunderstood. I thought that once I enabled two-factor auth for LastPass, it'd require that no matter what. Nope, just open the iPad app and no two-factor required.