We have 2 gds in Alaska. Things are rugged there, so whatever you decide to do, make it very strong!!!! My girls live w/o electricity and laundry is done at the laundrymat 3/4 of the year (when its cold). Hard on quilts!
There is no reason why it can't be "girly" AND Aussy. They aren't going to be 3 years old for ever. Since you are so far away, I'd make it with something relating to your part of the family. One of my quilts for Alaska was fish and ocean theme (I had 3 gds born one summer and made each of them a very different "fish" blanket). Something like that would be a possibility for you, also. Another (baby blanket) was a clumsy rendition of the northern lights we saw on one trip. But almost anything can be made feminine and cute while including some images of something Aussy. That way they can learn to be proud of that part of their heritage without even being aware of it, until later.
Kitten blocks mixed with Aussy colors (although, unless they live in the city they may not have kittens...eagle food), snowmen or women and cute kangaroos... Go look at fabrics and see what speaks to you.
I don't know if aboriginal patterns have made there way into fabric there, but they should have! I have a gift tee shirt and have been stopped when wearing it and told in an Aussy voice that it is a true rendition. And it is incredibly beautiful. Enough. Go with your heart.