When you raise a wyvern it says it need wyvern milk. You don’t need the wyvern milk. Cryopod it and it might change, you might have to cryopod it multiple times but if you don’t have a cryopod then you can still raise it but you may not get the imprint of it wants wyvern milk. Also when you raise it you can force feed it meat and it’s health will go up so if it’s food is all the way down it may not die.