Child’s electronic devices go off automatically when the table detects food on it and the chairs detect that the parents are sat down.
Toys that politely but increasingly insistently demand to be tidied back into their box, after they are left still, when the child is nearby.
Child permitted screen time is aggregated across all devices and is inversely proportional to sugar intake.
Toothbrush says “you missed a bit – this bit”.
Automatically raising toilet seats when gait analysis shows a boy has entered the bathroom (with option to put it down again, obv).
Towels that whimper softly but tragically if left on the floor.
RFID reader at school exit/entrance – makes sure that you bring everything back that you took in.
What else …?