Personally, I think I'd want to be sure that whatever problem I was solving this way couldn't be solved more generally, purely in the Edge domain? The edge-end indices don't exist in the Vertex domain, so will evaluate as 0.
But in the special case of separated edges in an edge-only mesh, it seems the explicit (1-value) interpolation from Edge domain to Vertex domain works:
So, for example, you can make instances on extruded edges like this: