Hello from Olney

Retired in 2017 after 54 years in the construction industry as a Chartered Surveyor.  During that time I used AutoCad LT mainly to interrogate existing DWG files to measure floor areas and the like.  So no heavy drafting, even though I did start out my career as a trainee draughtsman.

As you can see from my avatar I am a keen motorcyclist along with my 3 sons. But fair weather only these days having done all the wet, cold and windy riding in my earlier years when is was my mode of transport rather than a hobby.

I recently swopped my laptop hard drive for an SSD and the installation of AutoCad then refused to work and it wouldn't re-install.  So I needed to find an open source CAD package that would handle DWG files and this is the only one I found so will give it a try.

You probably will be disappointed, as LibreCAD dwg support has to be considered experimental only, may work or may not.
It's better to use an external dwg - dxf file converter like Teigha first. LC supports up to dxf 2007.

Is there a recommended cross platform and (ideally open source, but if not...) freeware DWG->DXF converter? Is this conversion workflow documented somewhere?

I don't know of an open source app, but I can recommend the Teigha or as it is called now, the ODA file converter. https://www.opendesign.com/guestfiles/oda_file_converter
It's still freeware, I think.
You have to set up an input and an output folder. I think you can do batch processing, but I am not sure.

just try it.