Maybe some early pranks. Most of what they do seems legit, fighting oppression and calling out bigots and disgusting people.

Does anyone happen to know if there is a N100 model that supports HDMI-CEC so I can make my old TV set smart with a recent Kodi and maybe some retro-games? But I'd rather not let it consume 9W or whatever such a machine needs all day long. So it'd need to start and shut down on its own. Preferably without manual additional steps involved, hence the CEC...

Sure. I'm not against people buying it. Including for novelty or be an early adopter. I've had a look at all the foldable phones in the store and I didn't really like them. I mean it's a nice idea, and I can see how I'd get some good use out of that large screen. But at least the Samsung one had a pretty noticable fold in the middle. And I can get a rusty used car for that kind of money. Or a mid-range gaming PC new. Maybe I'm just not the target audience. I never got why people buy expensive phones. My $350 one can do pretty much the same tasks in everyday life and also the camera and everything is decent enough. And I spent the extra money that'd get me to $2.000 on a laptop and other things. Yeah, but I know different people make different decisions and that's fine. I'd be in for something like a Nokia N950 if we want to change the form factor (and operating system for more diversity). But that's not happening. Or just a regular uninspiring Pixel with the price point of the 4a, just with the current (extended) update timeframe. That's something they don't do very often. Probably because of the smaller profit margin. But I also consider it an achievement and challenge to design and sell a device close to high-end specs, just for a fraction of the price.

It's too darn expensive for what it does. I'll stick with my $350 phone and a laptop or tablet for now.

I think that's why I wrote about stalking, doxing and and the job of journalists. I think it's generally not well aligned to the job of a private investigator. I think you could do it as a journalist. Have some idea that someone feels fishy and see if you can dig something up and write an article about it. There might be some overlap with the two jobs in the methods. And OP's question came from a story idea. Maybe there are unprofessional investigators without morale? I think some professional with an interest to keep their job will certainly not cross the lines, do illegal methods and then also document it... They'll probably just refuse to do that job.

I think we have some more pressing issues with email. We need a new protocol that effectively fights spam, phishing and adds encryption and signatures. And that protocol needs close to 100% adoption around the world. I don't mind if we also go ahead and make it more efficient and add features like automatic deletion etc. But that's just the cherry on top.

Then I misunderstood what the question is about. With your definition and the original question in mind, it'd boil down to doing journalism. Of course that isn't illegal. But it also has some severe restrictions when it comes to individual people and their private life. You can't just doxx someone and publish everything invading their privacy. And here also different rules apply to the person investigating and the person publishing the information. But the rules for private investigators still apply.

And I still think a good part of what a private investigator does is things like finding out if someone cheated on their spouse. And that includes following people. And they better not tell how much they exactly followed someone, but instead only take a picture when they actually caught their suspect doing something wrong. Which they can't do with the premise of this story... Without a clear goal, they'd have to become more like a paparazzi. Which might be closer to illegal and the movie PI than their usual job.

And sure, other parts of their job is probably digging through social media, paper trails when it comes to money, investigating if someone embezzles money or is in breach of a contract. But I don't think it applies fully in this situation.

However, if you find a politician embezzles money, or poses for the working class and secretly owns 5 mansions in Miami, and you call them out... That's regular journalism. You just need to make sure to obtain that information legally. Or claim you got that from a mysterious source. And adhere to the standards of journalism. You can't publish when they fetch their kids from school and then someone goes ahead and uses that information to harass their 12yo daughter.

It's the internet. Lots of people write silly stuff and blast their uninformed opinion around. That also happens on the Fediverse. They do it for various reasons. And it's easier to do it pseudonomysly than in real life. Also you'd expect some left-wing people to pop up on Mastodon, since they've left Twitter and Mastodon is the number one alternative.

Coffee

For AI training? Or why would someone specifically pay attention to watermarks? I believe there are curated datasets out there. And watermark detectors to weed out watermarked pictures from a pile of data. I don't think the general public sorts by presence of watermarks...
And I'm not sure about games and webcomics. They all have some logo somewhere, because they've been made by someone. If you don't want that, you're looking for white-label products. I think in the realm of privacy, and those product types, that's a small to non-existent niche.