(Background: I work in product design/new product development, and conceivably might have designed this thing! If any of those were still designed in the Western world. Which they aren't. I have designed some stuff like it, though!) Oh, great, this debate again! I shall use this post as ammunition next time I am arguing with our stupid design team about why we need an off switch on the stupid product we are designing…
You might enjoy [1] about a microcontroller that's ~3 cents, in quantity 10.
Of course it's only one-time-programmable, and generally pretty basic. And that's a pre-supply-chain-crisis price - these days prices have risen to 9 cents [2]. Still very cheap though!
[1] https://www.youtube.com/watch?v=VYhAGnsnO7w [2] https://www.lcsc.com/product-detail/Microcontroller-Units-MC...