How to export particle based instanced geometry?

im currently try to export an abc cache which is supposed to have instanced particles with geo as feathers.
They are part of a feather rig and while the rig is fast and does all well, exporting these seems impossible.

For some reason it skips the instanced geo when exporting as abc.
Making the “instances real”/convert also does not help, they still are skipped.

I tried this script But it takes ages and the result is out of scale.

I tried USD which works but it creates a super complex file with 100k nodes, which takes an hour to save and load …
FBX also seems to transfer the instances properly but not for animation.

My goal is to export the animated character into another package for rendering (sorry no cycles or eevee)
So either there is a reasonable way of simply baking feathers down to a cache and have them load up as needed or use the particles and hair orientation to rebuild the feather setup in clarisse.
In that case i need to store the scale and orientation per particle to export them … but i have no idea if Blender can do that.

So maybe someone knows how this could be handled ?
Thanks and cheers