We use exporters internally that plugin to for example Maya (2015) and export to granny. We intend to make these public
Sorry for the delay on those, I hope to get an update on the availability of those for you guys soon.
In the meantime I've already asked to update some related wiki pages. Our 3d artists are working on f.e. the Character
pages (work in progress) to provide some insight on the different required aspects of models and also provide some example files.