I've watched it about 50 times, and what bothers me most is the lack of any mention of the grab on Laporte's arm by the defender a second or so before the handball. The ball ricochets between Laporte and the defender. The change of direction of the ball suggests it hit Laporte's arm, but equally it also appears to have hit the defender's arm. Like you say, the grab was surely a pen, but the pen should be overridden because we scored despite being fouled. Suspend VAR and only bring it back when it's as absolute and instant as goal-line technology.