My wife’s works in Aus as long as her Thai sim as on and set to wifi calling, if turn off wifi calling no messages come through. Otp from scb and gsb both come through fine when have wifi calling enabled
Much better to do it in Australia if possible as she will then be on a bridging visa while waiting for it to process, offshore you could be waiting up to 5yrs before if could be granted and she is then able to come to Aus
We have done all my partners visa’s ourselves without and agent and had them approved without any extra info requested or delays and well ahead of the immigration online stated usually timeframes for processing