It appears that Xsteel CAD files (.nc1) are supported in Autodesk AutoCAD (possibly with a plugin) and as such, it should be possible to convert them to STEP product files (.ste, but typically .stp or .step) or other similar formats. Alas, we haven't found any other relevant information about nc1 to ste conversion or other programs capable of it.
Updated: December 5, 2022