LibreDWG
From Wiki.OSArch
See https://www.gnu.org/software/libredwg/
Free software known to support DWG using LibreDWG is limited.
- FreeCAD from version 0.19 has support and you can read the discussion in Let's talk about libredwg support.
- GRASS GIS
See also https://en.wikipedia.org/wiki/.dwg