I’m sorry I didn’t see this sooner, life and work have gotten in the way.
if she is still around, definitely contact the National Great Pyrenees Rescue.
https://www.nationalpyr.org/contacts
For the matting, you have to be very patient brushing her out, some mats may need to be cut out.
Thank you so much for helping a dog in need. There are too many out there that need help.