One other way: change your password to a temporary one, give it to a trusted friend who changes it. You don't know the password, you can tell the truth to the border agent.
Once you're out of their hands, ask for it back and change it again.
Even if the friend is in the US, they cannot compell her/him to release it easily, US laws apply.
There must be a way to also encrypt the new temporary password with 2 keys so that the trusted friend cannot access your encryped content without your own key.
I don't see how any of these solutions help. At the US border agents routinely ask you to log into your email account and search your emails. If you refuse to comply it is much more likely they will not let you into the country.
So they don't just search your laptop they try and search online accounts also.
Once you're out of their hands, ask for it back and change it again.
Even if the friend is in the US, they cannot compell her/him to release it easily, US laws apply.
There must be a way to also encrypt the new temporary password with 2 keys so that the trusted friend cannot access your encryped content without your own key.