They will get a $5 wrench and beat you until you give it up yourself, per XKCD https://xkcd.com/538/
In other words: this isn't a technical challenge, either you comply and give them your private stuff, or you're not going anywhere. Maybe you can con them into giving a 'public' part of the phone and pretending that's all there is, but again, that's social engineering and not a technical challenge.
We are simply not allowed to have privacy and also live a meaningful life. Everything we want to do now requires us to surrender our privacy. Transact with money, see a medical professional, travel internationally, etc.
In other words: this isn't a technical challenge, either you comply and give them your private stuff, or you're not going anywhere. Maybe you can con them into giving a 'public' part of the phone and pretending that's all there is, but again, that's social engineering and not a technical challenge.