She was human, was she not? Ergo, she was as sinner, like ALL humans since Adam. Was she still chosen by God for His Purpose? Yes, she was. She obviously was devout, but as human, a sinner.
So, a sinner saved by Grace.
Yes.
Ergo, she was as sinner, like ALL humans since Adam.
No. Our Blessed Mother was full of sanctifying grace from the moment of her conception until her Assumption into heaven. She was protected by God from the stain of Original Sin as a special grace of Christ.
Christ observes the 4th commandment to honor His mother. He does this perfectly as Jesus was perfect. Which is why Mary was full of grace.