Not related. Here is the opening of the LCMS explanation of Ash Wednesday.
The Ash Wednesday Gospel (Matthew 6) speaks against disfiguring faces to show others that you are fasting. People sometimes mistakenly think that's what the ashes for which Ash Wednesday is named are all about. Wrong.
The ashes are put on with the words from Genesis 3: "Remember, O Man, that you are dust, and unto dust you shall return." The ashes show not fasting, but DYING. They are sign not of practicing piety, but of the rock bottom reality of life in a fallen world. They announce to us: "I am dying...and so are you."
About the Norse religion... There are so many ideas and theories about Christians stealing from pagans, often contradictory, that any assertion is just plain meaningless. This is adiaphora, not Gospel and not theology.
Contrast that with the heartbeat of Christ - the very salvation of our souls through His Gospel of grace.
What contrast? No one says that Ash Wednesday is necessary for salvation.
As pagan practices were incorporated into the early church, they became a system of works, rituals, sacraments, etc., that substitute for the Gospel of Grace.
That the claim is made that Ash Wednesday celebrates Genesis 3 is simply a claim from a later time to backfill a practice incorporated from paganism. It is neither commanded to the Church, not instructed, nor modeled, nor written about before 100 AD.