glTF support
glTF is modern and widely adopted asset format. Blender and many other 3DCC tools fully supports it.
It could fit into OpenMW pipeline much better than proprietary .nif and outdated and sometimes buggy .dae (in OSG it works quite bad).
There are some feature-complete libraries:
About glTF and why we should adopt it: https://godotengine.org/article/we-should-all-use-gltf-20-export-3d-assets-game-engines