Is golytely (polyethylene glycol) used for any medical purpose except colonoscopy prep?

Occasionally. Once in a while I use go lytely or similar bowel prep acutely in a severely constipated or patient with a fecal impaction.
Maybe. Some gastroenterologist use it to treat chronic constipation by dosing a glass or two per day. However, it is commercially available over the counter as mirilax or glycolax.