Some people are already being forced at immigration to power up and unlock their devices which can then be taken away and data copied before returning and either allowing entry or not.
Currently happening to selected people, but many calls to make this mandatory or have to do it up front.
Likewise you now have “voluntary” questions about social media accounts on the ESTA (visa waiver you fill in and pay for online now, else no fly). Just done a trip and between a group of us the difference is that by not answering those questions it seems to take a day or two to get approval. Answering them it seems to be instant. However again it’s been suggested this could become a mandatory question and extend to having to supply your social media account passwords also. Or alternatively being asked this at immigration and if you refuse, you’re sent back home.
The suggestions have to be approved in law of course.
As for “nothing to hide”. It’s more a problem of trusting their security with my private information and also if you have corporate information. I would not be able to take company devices or have company email and files on them.