I built an Engine monitor for a friend's Europa Experimental. I used an Atmega2560 stock.
There are 2 2-line OLED displays in the airplane but the serial sensor stream is formatted faux-JSON and feeds into NodeRed on an old laptop.
https://www.stm32duino.com/viewtopic.php?f=42&t=959&p=9015
As there are 2 thermocouples and numerous thermistors and analog inputs being acquired, the 2560 "loop" is approximately 650mS. This certainly suggests that something more robust than a 2569 @16MHz will be required.