Referring to Mary as the NT Ark of the Covenant is a stretch as the AOC was representative of the Mercy Seat of God. It was kept in the Holy of Holies in the temple and was visited only by the Levite high priest once a year for the Day of Atonement sacrifice.
God's special Shekinah glory dwelt on the Mercy Seat atop the Ark of the Covenant. According to the prophet Jeremiah (3:15-17) the Ark of the Covenant will play an important future role.
The Ark of the Covenant was made of acacia wood and covered outside and inside in pure gold. It was 45 inches 27 inches by 27 inches. Three sacred things were placed inside the Ark of the Covenant. Inside were Aaron's sacred rod, which was used to perform miracles in front of Pharaoh; manna, which God gave the Israelites to eat in the wilderness; and, the Ten Commandments on tablets of stone.
To the ancient Hebrews, the Ark was both a divine manifestation and a talisman so powerful that they carried it with them into battle — a weapon of God.
With that history, I fail to see the comparison of the Ark to Mary. It sounds as if you are saying Mary is the new way to come into the presence of God. When Jesus was crucified, the veil that separated the Holy of Holies from the rest of the temple was ripped into two, showing that we can all approach the throne of God and the need for an atoning sacrifice was no longer needed. Jesus was the “Lamb of God who took away the sins of the world” and was the propitiation (satisfactory payment) for our sins and not just expiation (a covering only until the Messiah came).
Well, Mary IS a new way to come into the presence of God as she delivered Him, literally.