I wanted to use a workflow like this years ago working with Apress. Possibly (hopefully) things are better now, but at least at the time, all their tooling expected Word docs as the input, and you had to use a very specific stylesheet (including goofy stuff like magic text strings to insert images).

There were also some manual transformation steps occurring on their end, because there was a cutover point where the Word doc was no longer accepted and you had to just quote page and line numbers to get further changes made.