Marty make a cone/cup from Arnold towel, rag, paper towels what ever to sit the gosling in. Every 20/30 min offer it tepid water (1cup)with 1 drop of poly visol and 1 tsp sugar mixed into it. Dropper or qtip to offer fluids is best. The poly visol is a key part as it offers vitemins to them that are sometimes desperately needed when weak from an assisted hatch. Try and avoid mixing salt into their water, sugar gives carbs and energy in combination with the poly visol (no iron version).
We have saved many a hatchling with this. Is, have told it to many others who have saved hatchlings. It does work, I know you have warned people polyvosol is for humans, but it is a well used item as are many other human made items for animals. Vet wrap was first a human medical wrap know as koban.