Geese and Swans might too. If you crossed Black Swans and White Embdens, you might not have to deal with the grays black inhibitor gene. Someone might know the chromosome count for geese and swans. If they are the same, offspring snould be fertile. If not exactly the same, One gene might be sexlinked and a cross one way might produce one sex that is fertile, a cross the other way might produce the opposite.
Domestic cattle produces fertile bulls.
Good luck, which ever way you choose. That helps a lot. It would be the equivalent to the black inhibitor gene that causes barring in Rocks and Laced Blue in Andalusians. If that gene exists in geese, that might be why they are gray and not black. This is a private posting area.