Question How to export only keyframed animation bones from blender?

I'm trying to export a simple hand gesture animation I created in Blender to Unity.
The animation only affects a few bones as you can see here (these are rotations only):


The problem is when I import the FBX file in Unity I get a keyframe for every bone in the figure:

I also get the position keyframes, even though I only want rotations.

So in order to keep my animations clean I would then need to scroll through the several dozen keyframes, and find the ones I don't need and delete them. This is a very tedious process, specially since I want to make several animations and there's also some trial and error involved.

I've tried every possible combination of export settings. Disabling the ones that one would thing would work: "Key all bones" and/or "Force Start/End Keying" just results in no animation data being present in unity.

Is there any way to export only keyframes I want?
If not is there any tool that can detect when keyframes don't change, or maybe filter to only select the ones I need, so I could copy them to a new anim file?

 

I'm looking for the solution to this too. Nobody seems to be talking about it.