>another (probably pricey) MCU The R7FA4M1AB3CFM costs $3.42 at quantity: https://www.digikey.com/en/products/detail/R7FA4M1AB3CFM%2523AA0/559-R7FA4M1AB3CFM%25

>another (probably pricey) MCU The R7FA4M1AB3CFM costs $3.42 at quantity: https://www.digikey.com/en/products/detail/R7FA4M1AB3CFM%2523AA0/559-R7FA4M1AB3CFM%2523AA0-ND/10447195 https://www.digikey.com/en/products/detail/R7FA4M1AB3CFM%252... For an Arduino board, voltage and pin compatibility is an absolute hard requirement. (The only reason you use Arduino is to use Arduino software or existing peripherals/shields) ESP32 has fewer pins and is a 3.3V part.