Something else I wanna mention, not sure if it was already said, but Pyrenees are a wandering breed. They like to wander and do perimeter checks. So hopefully you won't have too much of an issue with wandering.
Also, they are bred to protect livestock, and they can and will kill anything that...
Once she get's older and bigger, I suggest using a prong collar for walking on the leash, sit, and stay...more important stuff like that. I also suggest using a shock collar for when you're teaching her to come when off leash.
In my opinion, dogs won't listen as well when training with treats...