Thanks for the feedback! I'm actually working on a pivot system right now!
Textures in fbx files are a massive pain, since the fbx file stores an absolute path to the texture file. If the model is moved, then the reference to the texture can be lost. How a program accesses the texture file is dependent on the program, and so it can be a massive pain to get the texture references working correctly in multiple different platforms.
I'm hoping to look into exporting as gLTF files, which may have better support for programs than fbx files.