To my understanding, thanks to the US's uncomfortably lax privacy laws, immigration officers are allowed to demand you to let them search your phone. If you have fingerprint unlock they can just straight up force you, but if it's a passcode you can refuse. Naturally though if you refuse you're probably not gonna get admitted. Is it at all possible to go back without having a permanent black mark on your record? Eg. paying for your own flight tickets back and going home without a refusal technically there? Or will you have to accept the searching of your phone if you want any chance of coming back to the US (or even any of the other Five Eyes)?