The recent demonstration of MoSi2N4 and its exceptional stability to air, water, acid, heat has generated intense interest in this family two-dimensional (2D) materials. Among these materials, NbSi2N4, VSi2N4, VSi2P4 are semiconducting, easy-plane ferromagnets with negligible in-plane magnetic anisotropy. They thus satisfy a necessary condition for exhibiting dissipationless spin superfluid mod...