Export to geometry format like iges or step rather than mesh format like stl

Hello to the threejs communauty,

I have developed a simple 3D geometry editor, and so far I have a working stl loader and exporter, thanks to the existing libraries.
Now I would like to feed a physic simulation software called COMSOL with geometries made in my threejs editor. This COMSOL software does take stl as an input, but then the possibilities are very poor, I cannot perform the simulations I need. It would work much better with step or igs which describe the geometry rather than the mesh.

From my searches it looks pretty clear there is no step loader for threejs, but what about the other way around ? Can I create a .stp or .igs in my threejs program ?
As a backup solution I have read maybe FreeCAD could do the stl to step conversion.

Thanks for the great tool, Gérald.