Not as part of core GrapheneOS, but an app called “Private Lock” can detect sudden force via accelerometer and disable the fingerprint based unlocking for next unlock.
But yeah, an erase passcode feature with opening a decoy profile would be a great feature to have.
E: grammar
Good for privacy! But I really doubt it would work for all recognition systems.
Some funny pitfalls that may occur - Self driving cars would prefer to hit that person if had to make a choice between him and some other human. And, there is possibility that the Street mapping cars would not blur his face for the lack of detection.