I'd like to import a *.dxf
-file into GIS 3.10 LTR.
Does the DXF2Shape plugin available for this version of QGIS?
Option 1: You don't need a plugin for that. You can import DXF (or DWG) in Qgis with a built in option: go to: project >> Import/Export >> Import Layers form DWG/DXF . Later you can export or save it as a shapefile.
more info here: https://docs.qgis.org/3.10/en/docs/user_manual/managing_data_source/opening_data.html?highlight=dxf#importing-a-dxf-or-dwg-file
Option 2: Install the plug-in AnotherDXFImporter (https://plugins.qgis.org/plugins/AnotherDXF2Shape/). This plug-in let you import DXF files and save them as shapefile.