You talk as if sinlessness is a matter of degrees. The bible says Romans 3:23For all have sinned, and come short of the glory of God; Everyone is a sinner. By the way this includes Mary. Romans 8:3For what the law could not do, in that it was weak through the flesh, God sending his own Son in the likeness of sinful flesh, and for sin, condemned sin in the flesh:
Once you have supernatural life, once sanctifying grace is in your soul, you can increase it by every supernaturally good action you do. A righteous person’s prayers produce results. There is no person more righteous than a person who has not ever sinned.
What is supernatural life and what is a supernaturally good action? Hypothetically I suppose this is true, but Romans 3:23 makes the point moot.
James 5:16 “Confess your trespasses to one another, and pray for one another, that you may be healed. The effective, fervent prayer of a righteous man avails much.”
1 Peter 3:12 "For the eyes of the LORD are on the righteous,
And His ears are open to their prayers;
But the face of the LORD is against those who do evil.”
The righteousness talked about here is the righteousness we take on through faith in Jesus Christ
Isaiah 64:6 But we are all as an unclean thing, and all our righteousnesses are as filthy rags; and we all do fade as a leaf; and our iniquities, like the wind, have taken us away.
Jeremiah 23:6 In his days Judah shall be saved, and Israel shall dwell safely: and this is his name whereby he shall be called, THE LORD OUR RIGHTEOUSNESS.
Mary gave us Jesus by her consent to the Will of GodNo greater gift for man could ever be possible; she gave us the gift of the Savior for our redemption. Mary continues to be a conduit of God’s graces because it is God’s Will, but all of her graces come from God. We can do nothing apart from God’s grace.
John 15:5 “I am the vine, you are the branches. He who abides in Me, and I in him, bears much fruit; for without Me you can do nothing.”
Mary didn’t give us Jesus. God did. Mary was just the vehicle by which He entered the world, but then so were all His ancesters up to and including Adam. She is a conduit for God’s grace only in so far as she she was His mother. She has nothing to do with the dispensation of God’s grace. John3:16For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life.