Western Australia so not other country then.
I like the One Planet Cocoon in a Large and would buy one if and when I ever need a new sleeping bag
https://www.oneplanet.com.au/product/cocoon/It is a very breathable shell fabric so it is for use in a tent or good shelter to keep the breeze off
Plenty of room for me and my wide shoulders without the expander wedge, but otherwise a quilt is a good enough option for non-freezing weather.
I've experienced temperatures well below freezing when I was living in The Alice and I understand outback WA can get pretty cold sometimes.
If you can sew a quilt is a good and relatively easy DIY option in synthetic APEX fro RipStopbytheRoll