Skip the Australian release. It's the only 4k version of Parasite in the world without a Dolby Atmos Track. Having watched this with Atmos for the first time recently after watching it about 7 times prior on the standard Madman Blu-ray, I can tell you it is worth it and adds significantly to the experience
Also, can't be 100% certain, but due to this version being published by Universal, there's a chance the included standard Blu-ray will work here as well. Universal discs are generally region-free in my experience. (Update: blu-ray.com suggests the standard Blu-ray is region locked so YMMV)
awesome movie.