You have set up fake accounts with Apple, Google or Microsoft

Your device should only contain minimal data. There is a general risk that your device will be analyzed by mobile forensics at these borders and automatically searched for opositional criticism. You could face rejection at the border or even imprisonment. If you are unable to create such accounts beforehand, you should decouple your device before crossing the border so that you no longer have access to your cloud data. You can connect your device to your real accounts after crossing the border. You can also consider purchasing second devices for certain countries if you have to travel frequently.