The odds that the US government will attempt to examine your phone are low; unless you are already a target for one reason or another.
If you are a US citizen then they can seize your device but they can't deny you entry to the US and can't compel you to provide a password/pin.
If you aren't a US citizen then entry can be conditioned on providing complete access to your device.
If you need to enter the US regularly then retain a US law firm to purchase a pixel for you, load GOS on it, and transfer any data (in a quantum resistant encrypted format) via the cloud. When you leave, have the law firm store your device until your next trip.
Bluntly, if the US government is actually a serious part of your threat matrix then do not take anything but a sanitized burner phone through customs.