As a former embedded SW engineer, I'm willing to put money against it (for 99% of the use cases for micro controllers by volume), most of the ones I worked with

As a former embedded SW engineer, I'm willing to put money against it (for 99% of the use cases for micro controllers by volume), most of the ones I worked with were 8 or 16 bit, had at most 1 MB of volatile storage, and you were lucky if you had 1 MB of RAM to work with. For my area at least, we're talking about the microcontrollers for your car's key fob, your car's instrument cluster, etc. Every electronic component in your car has an embedded microcontroller connected to the CAN bus. And cost is a big issue. High end electronic might contain more powerful micro controllers, but I doubt that by volume it makes a significant percentage of the microcontrollers in circulation.