Geese are able to store excess calcium in their bones and later use that calcium for laying. That feature comes in really handy when wild geese select a breeding area where calcium is hard to find. They simply stock up on calcium in good time before laying.
If they run out of calcium, their bone structure will suffer. This is also the case for chickens and ducks. But as long as they have access to calcium like oyster grit (and are not deficient in other vitamins or minerals), their bone structure will not suffer.
Your goose is laying fine, shelled eggs, she's eating her grit, and she has no trouble walking, so obviously she doesn't suffer from a calcium deficiency. Which means her bones are fine.
Please be careful. Too much vitamin D is harmful. Mild cases of vitamin D overload is pimpling of egg shells.
Please remember that nuts are a snack, not a necessary dietary supplement. Probably a way better snack than chocolate - don't ever feed them chocolate - but the calcium levels are about the same for nuts and chocolate. Nuts are high in fat and contain about as many calories as an equivalent amount of chocolate. Think of nuts as goose chocolate and don't despair if she doesn't want them.
