We tech guys keep thinking of tech solutions, but as someone who reluctantly has to cross a border of an even more hostile country every now and then, you have to remember that border agents are not stupid and will mark you as suspicious if your open profile does not look real enough or there are traces of encryption on the device (when they connect the phone to forensic tools, they can easily see if something looks off). Being paranoid about security is a huge red flag.

The only thing you can do is travel with a clean device on which you maintain a completely innocuous social presence, such as chats with parents and non-foreign friends, and some social media with normie activity. Even that would not be enough if you're an activist or otherwise personally targeted, as your real accounts are already known in that case and your only option is not to travel at all, but it reduces your chances of getting in trouble (or arrested, depending on the target country). Though it still won't help in the long run as security services collect and organize more and more data about everyone.

The full image backup solution solves that, as you never have to travel with your stuff and can upload and download it-

But also, things like the hidden OS, or shufflecake - they're building these so they're would be no traces. Which is why I said this sort of thing needs to be standardized - if every phone or device naturally gets extremely high levels of security, and it's built in by default to all of them- it's not unusual anymore, is suspicious. And stems the overall ongoing data collection on everyone that you highlighted.