[KJs6ZxELzQM37O]

I would not think it is fairly easy. The only real physical attack I can think of is to somehow to remove the delay throttles and brute force unlocking the device. This would be feasible for digits PIN, but not if you include characters. I am curious if you had something else in mind.

[grapheneos]

Rate limiting is implemented by a high quality secure element hardened against physical tampering. It isn't implemented by the regular SoC, RAM or the OS. It's not simple to bypass the throttling making a random 6 digit PIN secure.

GrapheneOS adds support for a strong passphrase to avoid depending on the secure element. It also adds the option to set a 2nd factor PIN for fingerprint unlock to make using a strong passphrase convenient via fingerprint+PIN secondary unlock while in After First Unlock state. Only 5 fingerprint unlock attempts are permitting and an incorrect 2nd factor PIN counts towards it so it's hardly a making the device protection weaker. Our PIN scrambling and the duress PIN features can also both be used with the 2nd factor PIN.