[msl]

You might want to check out The Amazing $1 Microcontroller [1] which explores multiple microcontrollers that could be had for less than $1 (when buying a hundred of them) in 2020. I haven't checked how much the prices have dropped since (if at all) but it could still be a good starting point when looking for parts at the 8021's price range.

[1] https://jaycarlson.net/microcontrollers/