What microcontroller are you thinking of?
Confining more strictly to $1.00, STM32F030F4P6 (48MHz 32-bit M0) is in spitting distance to a 386 or 20MHz 68030 for some workloads. (50 MHz 486-DX2 was introduced in ‘92, but the typical desktop PC of 1992 was much lower spec.)
https://www.digikey.com/en/products/filter/embedded-microcon...
To compete with a high end 486 desktop from 1992 you might have to pay a bit more than $1, particularly if you want floating point.