although Hashi died his cells were kept alive so in essence everything that he had while alive which would be wood style,height hair color, and his chakra is stored in his cells. Those cells being transplanted would still carry his chakra which happens to be Ashura chakra. i believe that what the sage gave them was more than simply chakra because if it were sauke would have awaken a regular one rinnegan not this one. As OT not for madara to unlock he went through a lot to awaken it including awaking to regular rinnegans