I am very sure of that when you receive packets from Australia they are free of Varroa. Otherwise I am sure of that you could not import those. The problem is, that varroa infection comes to those installed packages as normal. Robbery, Drones, wrong flight in you name it! Even if you fight Varroa and think you are safe there can be a re-infection from neighbour apiaries. Thatâ€™s why a late OC treatment is effective, because bees normally have stopped flying too.
The drawback from importing queens is, that you have to import every year, if you want to keep the characteristic of the bees.
Thatâ€™s the reason why I started queen breeding, so that I could control the queens I was working with. I was not going for colour, red eyes ore something like this, just for Steadiness, Swarming, Seek ness and Defend ness. Those are easy to visualise by a short look. Steadiness and Defend ness when you open the hive. Seek ness when you have problems but varroa. And Swarming if you see swarm cells. So a simple graduation (1 to 5) is possible. To this comes a building of an index so that selection of breeding/drone producing queens can be selected by this index. But this might bee too much for this thread.