Boost has enabled esim via their updated app. Download the new app then select your mobile. Select transfer or restore esim.
I transfered today took 2 mins on android.
https://boost.com.au/pages/esim
https://boost.com.au/blogs/help-topics/does-boost-have-esim-…
https://boost.com.au/blogs/can-i-re-use-my-physical-sim-afte…
Just use wifi calling on your Aussie local sim or eSIM? I suppose if you can’t wait til you at hotel then that’s a different story