What about one of those SDF code CADs but with FreeCAD's sketcher as the UI?
I'd imagine extruding a sketch into an SDF object is possible, and you could just only allow sketches to reference stuff in other sketches, or the bounding box cube of a sketch extrusion.
They'd need some better tools for referencing stuff between sketches but other than that, it seems like it's mostly all there.
And then at the end if you wanted a STEP I'm sure someone out there has got to be working on some kind of mesh to STEP thing that properly preserves design intent.
I'd imagine extruding a sketch into an SDF object is possible, and you could just only allow sketches to reference stuff in other sketches, or the bounding box cube of a sketch extrusion.
They'd need some better tools for referencing stuff between sketches but other than that, it seems like it's mostly all there.
And then at the end if you wanted a STEP I'm sure someone out there has got to be working on some kind of mesh to STEP thing that properly preserves design intent.