This is not... advice. But if anyone's actually going to do this, the method that's worked for me...

A couple weeks before your trip, factory reset whatever burner phone you're planning on using and swap your SIM card over. Install a few basic apps you wouldn't mind them looking through. Enable hotspot/tethering, and connect your other phone via Wi-Fi.

For a couple of weeks, use the burner as much as you can with what is available on it. When you're driving, us the maps app for GPS. Make and receive some calls, ignore some spam calls. Read the news. Get a few inane text messages conversations going, etc.

When you travel, leave your regular phone at home and take the burner. When it's searched at the border, it has enough activity to pass most initial smell tests. If asked, you dropped your other phone and didn't have time to get it fixed before your trip, this is one a friend lent you.

This has worked for me. Never _actually_ into anything illegal, but just apparently had a suspicious vibe about me or something because every time I crossed the border into or out of the country I was spending 4-5 hours getting searched. Didn't need someone going through my entire life going back decades every time--once was enough.