Great Pyrenees dogs are mostly white, but there are some who have that "biscuit" colored tone. Looks to me like your dog is probably at least half Great Pyrenees. I have a Pyr mix who doesn't even have fluffy hair, but she is definitely a Pyr mix. She has the personality and temperament, 100%.
If you feel that your dog has the Pyr temperament, you can use that knowledge to your advantage and study up on Pyrs and what it's like to try to train them.
I went through the same thing when my Pyr mix started showing serious guarding behaviors.
You have a very beautiful dog there!!! Congratulation
s!!! He is very lucky to have been adopted by you.
Here are pics of my Mokey just so you can see that Pyr mixes can look very different from one another. Mokey was born with double dewclaws.