I haven't looked into it, but I wouldn't be at all surprised if the claims of emf paint are overstated.

Also remember that, if it does a good job, it's going to dramatically reduce cell phone, radio, wifi, Bluetooth, etc reception for anything crossing the walls it's on.

This is well into literal tin foil hattery, but:

You'd have to check what kind of frequency range it actually protects against, and you'd need a way to test it (no doubt there is some fake emf paint around as well).

You could also wrap your walls in chicken wire and get a pretty decent Faraday cage effect for cheapish.

It'll also break your wifi and phone (if it works).

Unless you are running a spy agency, this is just a waste of effort IMO.

There are lots of ways to block those signals. Paint is a dubious method. Look into Faraday cages. Tin or copper ceilings and roofs found in old homes have a tendency to do this. Thick concrete works pretty well too.

Here's the thing - it will block all signals. Say goodbye to cell service. Make sure you have wired connections where you need them.

Just put foam on the walls.

RAM (Radar Absorbing Material) coatings have existed for quite awhile. We use them for all kinds of stuff in the military industrial complex. The main question I have is who is doing upkeep to make sure that material/paint is intact and still maintains efficacy. And also how much is that going to cost? This isn't new tech, but it sounds like some company is trying to market it to people afraid of 5G based entirely on the commentary here.

It's nice to know about, but imho, that's fairly high level paronia for the average citizen.

Reminds me of this picture.

“The things, you say,
You’re unbelievable.”

"counter measure" against what?

If you have in mind https://dl.acm.org/doi/10.1145/2486001.2486039 then yes, sure, might help against that but honestly if your adversary has this kind of setup, you are in trouble. First what kind of information are you preserving that they would not be able to get otherwise, e.g. just watch through windows, mirrors through windows, hacking Webcam on computers, toys, phones, etc?

IMHO that's like .0001% improvement for a lot of effort so unless you already are pretty much entirely offline, live in the woods with your blind closed, they it's a lot of energy for pretty much no change.