The oldest automated appliances were just complex mechanical timers sequencing various things on and off, and appliances haven't advanced that much. On/off motors, solenoids, sensors, and some series limit switches.

Probably the biggest new difference I've seen is brushless motors with variable frequency drives, which requires its own power control electronics and probably some calibrations.

So in my estimation not very many. Packaging it all up in a way that an appliance tech could be comfortable installing would be the hard part.