Happy to be corrected, but my take on this is that only plane (a RAAF Fairey IIID) has ever flown around Australia, and that was almost a century ago, in 1924. Every so called 'circumnavigation' since has essentially been a cross country, even allowing that some sectors might periodically pick up the coast.
While young Oliver O'Halloran and his ilk deserve every encouragement, and accolade, his route falls well short of a circumnavigation (which is something he would probably also concede). Take just one sector for example. By bypassing Cape York he reduces by two-thirds the distance needed to properly circumnavigate the Cape.
But clearly, I'm envious.