I hunt. If I am in the woods during hunting season, I have on orange as required by law. If I am in the woods during hunting season in plain clothes, I wear orange for my safety. Not all hunters are safe (I am not saying this little fella and his g'pa weren't...I am saying some people will shoot at movement, when they should be making sure they have a clear shot at an animal before shooting). Squirrel hunting is up in the trees with either a .22 or a shotgun. Yes, you can shoot them on the ground but they are much easier to see and shoot from above. While it is more difficult to injure yourself with a long gun than a handgun, it isn't impossible.
So, my speculation is... This sounds like the boy and his grandfather were very cautious and experienced. Wyatt was carrying the gun, got separated from grandpa and had a horrible accident. I think the family and LE are keeping quiet because the matter is settled, the child has passed away and grandpa is trying to overcome the guilt
If he had been shot with a different caliber, LE would have made a statement that they were looking to charge someone with homicide. I suspect they were able to tell from bullet trajectory that little Wyatt injured himself and unfortunately since he was lost and alone, there was no surviving it.
May he rest in peace and his family find comfort. So, so sad.