John 20:21 - before He grants them the authority to forgive sins, Jesus says to the apostles, as the Father sent me, so I send you. As Christ was sent by the Father to forgive sins, so Christ sends the apostles and their successors forgive sins.
John 20:22 - the Lord breathes on the apostles, and then gives them the power to forgive and retain sins. The only other moment in Scripture where God breathes on man is in Gen. 2:7, when the Lord breathes divine life into man. When this happens, a significant transformation takes place.
John 20:23 - Jesus says, If you forgive the sins of any, they are forgiven. If you retain the sins of any, they are retained. In order for the apostles to exercise this gift of forgiving sins, the penitents must orally confess their sins to them because the apostles are not mind readers. The text makes this very clear.
What the commentary about 23 makes clear is the person they want to hear your confession does not have the mind of Christ. If he did, he would know your sins.
You have to state orally, or put in writing, a sin you committed against me so I know to forgive you or vise verses.. It has nothing to do with forgiving a man's sin against God by a man.