The only mqo to obj conversion we know about, is using 3D models stored in .mqo (Metasequoia 3D) and export them to standard 3D Object format (.obj). This is for example done in Pepakura Designer, which can be used to process .mqo files for making paper models and then exporting these meshes to OBJ format, perhaps even for 3D printing. The same should also be doable with any 3D modeling tool, as long as it supports MQO format.
Updated: August 16, 2023