For (~100kg) pedestrian, I am sure the difference in lethality from being hit by a 1000kg vehicle vs a 3000kg vehicle is insubstantial. Where the weight would matter is for vehicle-vehicle collisions.
https://www.cdc.gov/transportationsafety/pedestrian_safety/i...
Weight is directly called out as a factor:
> SUVs can cause more harm to a person on foot when a crash occurs because of their greater body weight and larger profile