Can this be used for 3d path finding for spaceships, like the old decent games?
What old decent games are you referring to?
3D pathfinding is very expensive and is not something that is supported by the A* Pathfinding Project out of the box. You can use a point graph and arrange the points in a 3D grid like pattern if you don’t need a very large graph ( a large graph would be very slow using that technique ).