For a digital content creation tool studio (dcc) which has one tool (maya) and they use a intermediate format called (fbx) and you want to interchange a 3d avatar in Godot Engine.

If you want to amend the process to swap out maya with blender, you would need to understand how the fbx format works and also how maya, blender and Godot Engine works.

Sure you can outsource the library to an external project like assimp, but the moment a particular fbx is broken you basically start rewriting assimp. If the errors are close to 80% of the imported cases, you'd need to rewrite assimp.

Also fbx in Godot Engine is a reimplementation of FBX as there's no specifcation of FBX file format. This is similar to your vendor locked in description.

This isn't a typical enterprise data exchange process but maybe my change of the theme of the process can help.