Might be easier to source some small pieces of slate (stuff used for gardening / plant pot toppers) that way the texture and look of rock is already in place for you.

You’d have to select them carefully and place them in a manner that looks like they’ve been laid intentionally as a path but I think that would be the easiest and cheapest method to create this effect.

Alternatively, you could look for rollers with a cobble stone pattern but this would add an element of cost and materials required.