for those looking for how to integrate hands in UE4 here is a little gift - free hand interaction framework + shooting range demo. All released under CC0 licence, which means you can use it in your projects without any restrictions.
The key features are properly positioned and rotated hands with animations and 17 grab animations that can fit most objects, index and thumb finger interactions with objects, throwing objects, basic UI elements and teleport locomotion. The demo shows how to use these interactions, including multi object interaction, like reloading a gun or lighting up candle.
Hopefully you'll find it useful, and if you have any feedback shoot here.