That ultimately doesn't matter. You tell them it's a travel phone, because you fear losing your expensive regular phone. Your social media accounts have elaborate, long passwords that would be impossible for a person to remember and are stored in a password manager at home (countless formulations you can go with in this story).

At that point there's nothing else they can get from you, the odds are overwhelming that'll be the end of the discussion. There's probably a one in a million chance that eg the TSA might detain you for a few hours out of spite if they think you're screwing with them.