Someone was working on a GTK-MUI wrapper some years ago. I thought it was finished, but I've never seen anything come of it.
If you have a MorphOS machine,
Scriba seems to have some OpenDocument support.
The Amiga's best classic word processors - WordWorth7 and Final Writer 97 - are very capable. The only major downside to them is difficulties with saving/loading modern formats. I'm not sure how capable they each are with datatypes, but someone could write a format conversion tool and then tie it into either program with ARexx so as to be largely transparent.
