Big shoutout to @libreoffice - I'm writing and revising my #WritingMonth project on two different machines from completely different eras - 2010 and 2025 - using completely different versions of LibreOffice (7 vs 25) and everything works *flawlessly* between the two.
No one way conversions, no having to choose legacy formats, nothing.

ODT was, and is, still the best standards-based complex document format.