What’s the best way to generate unique rocks in Houdini using For-Each, VOPs, or any other method? I want the noise to vary enough that each rock has a unique shape, instead of repeating the same pattern. How would you approach this?

If your noise is driven by the position, you could simply offset the geometry a different amount on X at every loop. Could be driven by the iteration.

To get the iteration value, make sure you have a Block Begin node set to Fetch Metadata.

...From there, I only know the wrangle method so, not sure how to get the iteration attribute inside the Point Vop. I think your need a bind node inside the point vop.

Ita also very common to base your noise offset on $F
Then cache out a sequence of rocks, each frame will contain a rock with different shape

You can offset noise patterns on the same position with a VEXpression inside an attribute noise node so each copy takes on a different shape.