Looks pure to me. Lots of Pyrs have masks. Double rear dewclaws or lack thereof, are not proof of anything, except, if lacking or single dewclaw, they are not show quality. They are supposed to have double dewclaws, but lots of "backyard breeders", or people that breed as LGD, don't care what the show standard says. I would be more concerned about temperament and health, than purebred. A true LGD, should be cautious about strangers, so consider if that is something you want in a dog. Frankly, I wouldn't expect your golden to start living outside now, most of the Goldens I've known would be heartbroken if kicked outside, even with another dog. On the flip side, I've known Pyrs that prefer it, even when given a choice with an open door. I say, go meet her, and trust your gut. Sounds like you have enough dog experience for that. Meet the parents too.
