During the holidays people often visit. Some unexpectedly bring along children. Having gifts for these children can mean a lot.
Often people buy inexpensive gifts, and quickly add a gift card when someone drops buy. No one really believes the gift was intended for them, but the recipient is usually polite and thanks the person giving the gift. If the gift is candy or cookies one might simply say to the child that the gift is for the family. But children like to receive their own gifts. And children are more likely to believe the gift was intended for them.
In some cases, there is a sibling at home. Do not allow the sibling to feel left out. Send a gift to the sibling.