I did try pawpaws on the plants themselves with toothpicks (many) and none presented callus. The trees were in a woodland. I know I did at least 10 or 12 to find out if that toothpick method would work. I also did toothpicks on cuttings in my greenhouse and that didn’t do a darn thing, either.
If you want to root something, look at this. I wrote it. Now I don’t know anything about pawpaws from cuttings, however.