Interesting and both are sold out. They seem kind of rare. Probably for a reason! I guess it would be bad if somebody like…had a trashbag’s worth of them with “You Won 1 Free Bitcoin” noted and sprinkled them around commercial and public properties a 100mi radius. Or sent out 1,000 in the mail for example.

The reason would be that not enough of them sell to be worthwhile. Simply going from your description it sounds like the kind of product that could be designed and set up for manufacture in a handful of hours. But then what? I have no use for the product and even if I were inclined to ignore the ethical considerations, I doubt that I'd sell enough of them to recoup my time.

The people for whom this would be most useful already have the resources to build it themselves!

I built something like this using teensy board. It’s pretty simple. Mine had a button to activate it, and was not nefarious but could have been. Hope this helps!

https://github.com/joer14/hackers-doorbell

I see multiple listings on amazon for attiny85 boards: https://www.amazon.com/AiTrip-Digispark-Kickstarter-Attiny85...