Yes, agencies with more power will have more ways to force you. CIA will be able to fly to a dark site and put a car battery to your balls until you give them the PIN. Normal cops during a traffic stop will not have much ways to influence you beyond detaining/arresting you but any cop will be able to take your hand and forcefully place your thumb on a fingerprint reader. And courts say it's legal.

https://reason.com/2024/04/19/appeals-court-rules-that-cops-can-physically-make-you-unlock-your-phone/

Yes, steel pipe to the knee will work equally well against all unlock methods. Graphene OS is supposed to be extra secure to better protect you against tools used by government agencies and law enforcement. It's used by activists and such. IMHO using fingerprint on Graphene OS makes all this extra security meaningless because police can just force you to unlock and it will be legal:

https://www.techtimes.com/articles/303768/20240418/court-rules-thumbprint-phone-unlocks-used-police-force.htm

Police would not be able to unlock this phone if the guy used pattern unlock.