"...because DSFTools cannot process DUF files (DAZ scene/prop files)"

Sometimes, when there's only DUF files, you can use un-zipper of your choice to de-archive the DUF's DSF content. It will appear as an un-typed file, just re-name to .DSF and okay the 'are you sure' warning.

Also, if the OBJ+MTL files make 'absolute' path calls into author's folder tree, they're easily amended with Wordpad for even vast OBJs, and Notepad for MTLs.