We just completed a cruise from Hong Kong to Sydney.
I got a maya eSim for the entire trip, and it worked flawlessly in every port, including four in Australia. I think it was 39.99 for 10Gb for 30 days.
I was able to set it up and test in in NZ (as it also included NZ data) before we went. I just disabled the OneNZ SIM once I was on the plane.