I believe so. The package descriptions for most of the ZFS packages in Ubuntu mention OpenZFS, so it certainly appears that way.
You can still create pools that are compatible with Oracle Solaris, you just have to set the pool version to 28 or older when you create it and obviously don't update it. That will prevent you from using any of the newer features that have been added since the fork.
This is likely something like a FIDO token/passwordless setup of some sort (i.e. Windows Hello).
The thumbprint would just unlock the hardware device, so the thumbprint itself wouldn't need to be transmitted to your credit issuer. This gives you full two factor authentication of your identity because you need the hardware device (something you have) and your biometric (something you are). They also often allow pins (something you know) instead of biometrics as the second factor.