Sorry for the long response I just wanted to give my viewpoint along with recent travel experience overseas (even though I am an American).
I think the PP's point about getting spooked is more on the dot. I've watched a lot of Border shows from various countries (Sweden I'm presently watching) and there's a lot that people don't realize are things that have been the case for a long time (looking at phones for example is not new nor something only the U.S. does; mostly related to are you attempting to do work in X country without the proper work visa). Sweden allows this practice of going through cell phones and e-mails with immigration as well but would you think about that and Sweden in the same sentence? Probably not. Same with New Zealand, looking at your cell phone at the border is permittable but would you think about that and New Zealand in the same sentence? Probably not but it's been allowable there since 1996 (though of course back then that would have been computers more or less).
I'm not attempting to say you don't have a cause for concern but I would want to try and say a lot of this is being amplified (not without understanding why just being more practical about that).
Now I will preface this by saying we've not traveled to a country yet that we ourselves were required to get a visa so I cannot speak to that in personal experience. The closest we'll have is the UK trip with the pre-authorization (and subsequently next year with Switzerland the EES system and ETIAS maybe depending on when that starts).
However in 2023 we traveled to Mexico. That same year a cruise where we traveled through France (via Paris and yes we exited and re-entered through customs as we went out into Paris itself), Italy, Croatia, Montenegro, and Greece then flew back through Heathrow in London.
In 2024 via train travel went to Heathrow in London (and toured London), France (though it was to get to the rest of Europe but through French customs), Belgium, Luxembourg, Germany, Denmark and Sweden flying back from Denmark via Iceland (went through customs there) and back into the U.S. We actually momentarily forgot we had been through French customs and was thrown for a loop when in Iceland their customs asked "did you go to France on X date?" and we had to quickly remember oh yeah we did that. Then went to Japan in 2024 as well.
This year we just completed a week ago a cruise flying through Madrid, Spain to get to Lisbon, Portugal, Spain, France and Italy. Flying from France, through Madrid back into the U.S.
In all of that very recent travel I can tell you the place I felt the most at risk was Cancun, Mexico especially as there has been back and forth about how many electronic devices you are allowed without paying a fine as such people have been charged. However, in terms of my day to day safety I worried about terrorist attacks more while in Europe especially as we went through Brussels to get to Ghent weeks after that terrorist attack.
That said we have plenty of overseas travel we'll be doing and just make sure we keep ourselves as up to date as we can. As I said Japan was the place that gave me the most angst in terms of customs not because the process would be hard but because there was such little information as to what was legal and wasn't legal (like I wanted to make sure my allergy medication was okay). I didn't have to worry about how many contact lenses I could take to Europe for example but didn't want to run afoul in Japan and I wouldn't have even thought that could be an issue.
As an aside advising to take a burner phone is one of the worst advices I think has been put forth. If the Customs (in the remote chance they ask for your electronic devices to look through) asks for your electronic devices lying about having an additional one would be then giving false information not to mention would raise more eyebrows; i.e. it's a heck of a lot worse IMO to even think to do that but I digress. FWIW I jus traveled with 2 cell phones for our cruise because my phone is so old it can't support the cruise line's app which is used for the included wifi onboard. The additional cell phone will only work with wifi as it's not connected to a cellular company. If asked there is no way I would deny having that phone certainly isn't worth any risk on my part.
I hear your concern though
As a quickie here's the link about New Zealand
https://www.customs.govt.nz/personal/travel-to-and-from-nz/electronic-device-examinations/