As I have researched this further, it is fairly simple. I am not sure how to export the hair to Blender. But it is Alembic groom so it should come in as curves if you can. From there it is not possible to turn it into hair but you can give the curves thickness and render with the hair shader. I have done this from Maya.
The rest of it would be very straight forward.
Though I think the strength of this tool is to completely bypass a DCC altogether.
As assets in Unreal you can also swap out the clothes for armor and so on.
So a Blender workflow would be to rig you custom clothes and other assets with a mannequin compatible rig. From there you can use Mocap and also animate with a control rig much like MotionBuilder.