Is the floor surface important with ducks and geese?
It is very important. As babies, they need a surface they can grip until their leg muscles and hips are strong.
This means no slick newspaper or cardboard for at least a week. The best bedding is wood shavings or straw or a 1/2 inch hardware cloth floor.
You want to avoid slick surfaces for adults, too, to prevent leg injuries. You also want to avoid surfaces on which they can cut their feet.
Circulation is not great in waterfowl feet and a minor cut can lead to a nagging, swollen infection in their feet.