How does it work?
Select at least two nulls and click Points Follow Nulls.
This will generate a new path that will be connected to those nulls using an expression.
Tip: by holding shift, you can generate using any selected layer, nulls or not.
Use Static Path from Nulls to generate an expression-free path.
This path will initially be shaped according to the selected nulls/layers, but will not follow them as you move them around.