My old man has a bunch of .dox stuff saved. He has complicated large files saved that are not supported by any of the FOSS conversion tools. I’ve tried Libre office, Abi Word, and every command line tool and converter I can find. These are entire book sized files.
I have a W10 machine with Word. Is extracting the .exe and running it with wine feasible without making an epic mess or massive project of this?
Sounds like it’s actually a .doc file that has been renamed to a .docx for some reason. Real MS Word would probably still open it fine, but open source tools would fall over hard.
You mentioned you can’t decompress it either. If it was a real .docx you could rename the extension to .zip and unzip it with any archiver to see the contents. If the archiver complains about the format, then it’s not a real docx.