Those WiFi blockers actually do have a use in some industries. I know there are routers out there that if you switch WiFi off in the settings, it doesn't actually switch off. The only way to "switch it off " is with those Faraday cages.
One thing that I have seen that is actually ridiculous is those 5G blocking USB drives.
What they are, is a 1GB (sometimes 512MB) flash drive with a fancy case and hologram sticker on it. You can buy these ready made on Alibaba for $4.99 each if you're buying up to 499 of them, or $3.22 each if you're buying up to 4999 of them.
One prominent "company" selling these $350 each so they only needed to sell 7 of them to get into the profits assuming they bought 450 of these
Here's the one they're selling for $350. As you can see, it's identical to the Alibaba one but with their "company" logo engraved onto it, which the Alibaba seller will do for no extra charge.
It's supposed to work by
But then on the same page it also says
These apparently sold very well in 2020. Like to a point where trading standards had to step in and said people are being ripped off with these and gave an alternative link for where you can buy the identical flash drives for 1/10th of the price that these are selling for. This is something that rarely happens, and in this case when it did happen, it made the kinds of people who believe this stuff believe it even more.
Also the entire "audiophile grade" level audio equipment as well as computer mice garbage. One of the best things I've seen is a $80 gold plated S/PDIF cable with low dispersion high purity fibre core with carbon insulation to reduce electromagnetic interference. The computer mice thing I'm talking about are things to reduce latency. None of those things do anything. You're just spending $60-$120 on magnets to put on your mouse cable for a placebo. Just admit you're bad at FPS games and that a pro with a generic Microsoft office mouse will be able to beat you at any FPS game, no matter what mouse setup you have.