Using #3 could land you in jail indefinitely in the UK I believe: if they don’t believe you forgot the password, they can interpret that as a refusal to give them the password (or unlock the computer), and jail you for this… until you give them the password.
Which you can’t, because there is no password at this point. So either you admit that you just wiped your computer with the panic password, or you can shut up and rot in jail until you die.
You need a way to make them believe you. Covertly wiping your computer is probably not going to end well.
Author here; #3 also defies the use-case for a duress word. The attacker is supposed to be presented with what appears to be a normal login scenario while in the background sensitive data is being scrubbed or even have the routines remove the pam-duress module completely so there's no evidence there was a duress routine in place.
Real law enforcement agencies would also simply confiscate the device and hand it to a forensic team to pull a "golden image" from it to work with in lieu of a user session.
It's a theoretical thing under the Regulation of Investigatory Powers Act, IIR. It hasn't been tested. In practice under the law it'd probably be a stretch under a sensible judiciary since you can't prove a negative and thus can't prove you don't know something.
In a number of countries there is a defined offense, like in Australia if they don't believe you they can jail you for six months under the Cybercrime Act, 2001, or possibly 2 years (failure to obey a court order under the Crimes Act, 1914).
Which you can’t, because there is no password at this point. So either you admit that you just wiped your computer with the panic password, or you can shut up and rot in jail until you die.
You need a way to make them believe you. Covertly wiping your computer is probably not going to end well.