No. OSMD is a MusicXML library. But if at some point MNX becomes the new standard, we might consider it. I doubt that would be soon though, MusicXML is still the standard for exporting, and there are large libraries for it.

We're definitely not particularly interested in a standard that is still work in progress / unfinished.

Of course, other open source contributors are welcome to work on it, but I think it would be a gigantic project with hundreds of hours of work.