This should work like this.
import PSD/PSB layered files,
automatic and manual creation of a 2D mesh for each layer,
binding the 2D skeleton to the above 2D mesh using weight maps that are created either manually or automatically
having a mesh with weight map will allow nice deformation of the 2D graphics
then integration with the rest of the unreal allowing animation of this 2D skeleton mesh
this will allow creation of animated 2D characters
obviously colliders and physics and the rest.