To hand over I think there is lawful order. But there is no lawful order for giving encryption codes or passwords to lawenforcement as far as I know. And one is also never obligated to tell anything, that could might be used against me.

You are right, there is exactly a law for that, it's called a self-incrimination protection. And while they may forfully confiscate the device, they can't force you to reveal the password. What is more the UK is the only western country which broke that rule. It's basically another russia/china. But instead of using a duress pin, just set a wipe timer for X minutes before entering a dangerous area.

How do you do that? Right now, I only have configures duress pin.

Look for an app called Wasted: me.lucky.wasted It has a sheduler, which is times out (you wont unlock) it will wipe the phone

So a geofence timer that auto wipes your device. This should be a default in a lot trust society.

Yes but no. Such systems have to be simple. The more complicated the system is, the higher the chance it will have a bug. A geofence is hard to enforce/detect and needs a lot of variables to work. A neat idea, but very hard to implement correctly