Home made pie or cookies and brownies always go over well. You can wrap them up in a foil container with some of that red cellophane wrapping and a bow. That way, it is clear that the item is a gift rather than just a random item that you brought for a potluck. Then the hostess can either open it right then, or open it later.
At my family’s parties, everyone always brings something, even if it’s not specifically a potluck and everybody is happy with that arrangement.
But like @Jleslie said, she and her family do not have that same tradition, so if you wrap up the pie as a gift, the hostess can make that determination as to whether to put it out on the table for the whole group, or to take it home, as her gift and eat it later.
But flowers are also, always welcome.