That Fusion still has not OBJ export is beyond my understanding - it is so basic.
The build-in render engine is nice for quick images wihtout high expectation but pales in comparision to what a pro needs when you have to do a real product rendering and design your shot.
For that Fusion seriously has to offer an OBJ export and not STl by part or old school DXF via the A360 web.
Currently you force us to use a different application to generate the OBJ mesh like MOI or Rhino.
So please include OBJ in the ecport menu or also add to the STL option when in context menu