Talk:Viewer Engines
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"*.gltf file formats are associated with the proprietary Unity *.fbx"
Huh?
.gltf, "Graphics Language Transmission Format" is an open format managed by the Kronos Group. It's also now an ISO/IEC standard. See [1] There are many systems which understand .gltf. Blender exports it and imports it.
.fbx is a proprietary format owned by Autodesk. See [2].
Unity owns neither of those.