Given files by client:
QGIS doesn't like it; FREECAD doesn't like it; RhinoCAD doesn't like it or Illustrator.
QGIS > Project > Import as .dwg/.dxf actually asks for .gdb, which doesn't help.
Found previous answer here: Converting .dwg to .shp using QGIS?
but it's not complete and from 2012.