Boy I've been looking all over for how to do this and haven't had much luck at all. (Though, to be fair, I haven't tried any of the online converters since some of what I want to convert I don't want to upload)

But, as the title says, I'm hoping to find a way to reliably convert some large docx documents, that were created in Word's 'Outline mode', to clean OPML files. (I'm using Bike as my outliner software, if that makes a difference).

Pandoc gets close - it properly brings over the tree structure - but none of the actual body text is preserved. A rather key part of the document!!!

Here's a link to a sample file that I've been using: https://www.dropbox.com/scl/fi/vpq3l5rqssszug5gt02h4/Generic_Word_Outline_Test.docx?rlkey=jrs0qnkf40rad2y24dl6q955r&dl=0

and, in case I'm missing something, here's the pandoc command I've used:

pandoc Generic_Word_Outline_Test.docx -s -o Generic_Word_Outline_Test.opml