Are their any alternatives to surgery for gastroschesis?

Depends. If you consider death a reasonable alternative than you can skip the surgery. This defect results when the intestinal contents are open to the outside through a midline defect in the abdominal wall. If surgery is not done to move the contents back into the abdomen and close the open defect, germs will invade and trigger blood poisoning and death.
No. With gastroschesis, the bowel is exposed outside the abdomen through a defect in the abdominal wall. Treatment involves replacing the bowel into the abdominal cavity and repairing the abdominal wall. Sometimes removal of a portion of the bowel is necessary.