bake animation from one rig to another

Hi everyone, I’ve created an extensive IK/FK action driven armature and created some walkcycles. Now I want to export the deformation rig to a game engine, but I don’t quite know how to do that without the rest of the rig.

I now tried to duplicate the rig, delete all the drivers/handles/poles etc. on the duplicate and applied a copy transforms constraint to each bone individually and connected them to their equivalent bone on the original armature. Now it moves the same as the original rig, but I can’t seem to find a way to save the deformations as keyframes. Each time I set keyframes and delete the original mesh, the animation either doesn’t work at all or is not looking like the original at all.
I hope what I want is not impossible :smiley: