The MetaHuman Devkit is an evolving collection of MetaHuman character technology that you can integrate into the platform or application of your choice outside of Unreal Engine. The MetaHuman Devkit is maintained by Epic Games.
OpenRigLogic
The MetaHuman Devkit starts with the OpenRigLogic repository, containing the RigLogic and DNA libraries. You can use these to load a MetaHuman character with the same runtime rig evaluation as Unreal Engine.
Both are available as native C++ libraries with Python bindings, and released under an open source MIT license.
You can find further documentation in the OpenRigLogic repository.