I am going to see if I can get someone to crush-test it. I've had the car up on it for 2 weeks (Nissan parts is VERY slow), and I will take a look at it afterwards to see if it is cracked or deformed.
Force is between 200-400 lbs/in2 depending upon whether you use a jack or jack stand. A single 2x2 lego can support 950lbs (around 3800 lbs/in2) without infill (ABS).
And there is really no reason to get under a Leaf, so not the same issue as jack stands on an ICE vehicle.