I have also been looking for this solution for the past few weeks, and I have not found a solution yet. Each Maya usd export plugin has it's issues. The Multiverse plugin does not support blendshapes yet. The Autodesk plugin loses the joint positions. The closest I've gotten is exporting fbx from Maya, converting fbx2gltf with the facebook command line utility, and importing the gltf into scenekit. The only issues are that the blendshape names don't translate over. The are listed as numbers (0,1,2,3,...),and the geometry that the blendshapes deform don't have any normal data in the vertices, so it looks faceted. Also the joints for the skeleton are all translated to the origin. If anyone has a solution for this, please share!