Actually, speaking of Kodi, at least, I found an app that might work to make it easier. It's called
Samsung Phonecast VR Beta and it's essentially yet another video-watching app, but it's designed to take non-VR video apps on your phone and essentially provide a VR wrapper. I don't have Kodi set up, but it's on the list of compatible apps. I tried it out with Plex last night and it worked great.
I don't know if Optus is compatible with it or not, but it might be worth checking. If it's not, maybe you can contact the developer and request it.