I have been thinking about the same things from the “bottom up” for a while now.
I like that you are taking this from the “top down.”
This was were I started and it burned out without much going much further:
From an earlier thread that was slightly related - how much computation does a critter need for the hardware it is equipped with and the environment it inhabits? This is the computation that must be performed with the spine & lizard brain augmented with special hardware like the cortex. (a math coprocessor?)