Still, I understand the top layer composition matters a lot in terms of how it could absorb an impact. Was it full of water? Earth? Sand?
We're talking about the time before the continents had formed, the scale we are looking at here is non-intuitive.
At that level of impact energy everything starts to behave like a fluid, even planet earth, so whether or not the top layer composition was water, soil, sand or rock is not that important. What's amazing is that there are traces left that much later, even more how large those features are. That's a testament to how enormous the impact must have been.
Original impact crater estimated to be 300Km in diameter. They think 70 cubic KM of soil was vaporized. For comparison's sake Mt St Helens explosion vaporized 1 cubic KM of soil and rock. Chixculub crater is 150Km in diameter, much much newer, but completely buried.
Still, you'd have to think we could estimate how big an object would need to be to carve out that much bedrock, assuming a given amount of topsoil.