I bought an eSIM at SYD on arrival just a few days ago from OPTUS. Took under 5m; paid AUD$60 for 60GB of 5G data for 30 days and unlimited local calls + international calls to a large number of countries.

I believe you can do it entirely through their app as well, at least on iOS, though I haven’t tested how well this works with foreign IDs in practice (it claims to accept international passports).