I'm trying to build an operator that moves selected objects to world origin (ignoring Z axis), runs 'Export FBX' operator and after execution (either finished or cancelled) the objects should move back to their original locations. The problem that 'Export FBX' is a modal operator and if I write 'move objects back' code after bpy.ops.export_scene.fbx('INVOKE_DEFAULT') , it executes right after the operator was called even if user haven't exported objects yet. So pretty much the objects should stay at world center until user clicks 'Export FBX' or 'Cancel' button because objects need to have their pivot points at the center when I import them to other programs such as Unreal. I can't wrap my head around how to do it. I was thinking of something like "if bpy.ops.export_scene.fbx('INVOKE_DEFAULT') returns {"FINISHED"} or {"CANCELLED"} -> do the thing", but it returns {"RUNNING_MODAL"} on call. Hope it makes sense :D Help please! I'll try to attach the code in comments as it says 'failed to upload an image' when I try to attach .py file here.

The blender conference is currently on going, videos can be found here https://www.youtube.com/@BlenderOfficial Good videos on gaussian and industrial applications.

I finally got my add-on working and packaged; I successfully installed it on another computer. It was a tricky first add-on, and I really appreciate the help I've received here. Huge thanks to @Victor Stepanov! I'll put it up on Github and make it available on Gumroad and Superhive for anyone who wants it off the shelf.