Here are links to various feeds from rural fire authorities around Australia (links updated 28 December 2022)
JSON and RSS files with spatial data are handled nicely by GDAL, which drives the "sf" library in R.
South Australia warning data with spatial info is locked down using HTML referrer checks. If you are handy with object inspectors and CURL then you can obtain the GeoJSON files. Look for URLs that begin with:
These sources have lat/lon data in them, but are not native GeoJSON. They are intended to drive HTML maps.
This is quite complex XML, so if you are a wizard with XML then this is probably the way to go.
This map was produced using these feeds at a time when there were active fire events in every state/territory in the country.