A blender 2.8 script that exports actions as separate fbx files for use in Xenko.
Install the addon and push f3 (windows default) to open the search. Type in Split Animation Export and select it. It will export all actions that are saved using a fake user (have the little F next to them) as individual fbx files in the same folder as your .blend file. The naming scheme is blendfilename_action.fbx. Import to xenko. Every fbx contains a single action, the mesh, and the skeleton.