You are probably gonna think I'm a real ninny muggins, but is pine straw simply dropped pine needles from under pine trees?
Yes, though more specifically the longer needles of the southern loblollies, longleafs, etc.
Any old pine needles or old leaf litter would share the qualities that make it so great as a chicken enrichment material -- namely, dig-ability and bugs -- though I personally wouldn't want to have to handle spruce needles and would choose something else for my own sake.