if I was travelling abroad I would not be bringing anything that has universal access to my accounts or data (primary phone for example). I would most likely get a new device loaded only with what I needed to get things done using a new account I transferred money into. For the most part I would not expect any issues but the laws at most borders, even US international borders generally say they can clean you out of all your data and force you to log into any devices you have with you. So the 2 countries mentioned are only part of the story when it comes to privacy when travelling international.
100% you make your own choices and the tools available offer various levels of true privacy. I do tend to agree that if you carefully select your hardware then roll a project you trust onto your system you are likely 1000x better than any off-the-shelf big-brother setup.
There is no easy answer to 100% verifiable and trustable secure systems at this state in the industry. Though I expect that to change over time, even lithography is starting to become a workshed hobby.
And they are going to know the differences between my flagship loaded with creds and the base model i just bought and loaded just the travel apps? I didn’t say don’t bring anything, I said don’t bring anything with real access.
I don’t care about privacy more than I care about having my gear confiscated and it taking months to return should they decide to make me thier day.