Yikes. Where is it even officially taught that Peter is in Heaven actually opening and closing the gate, or have you moved beyond what Rome actually teaches, while censoring others for teaching what Rome does not officially say?
As far as the keys being given to Peter, this goes with binding and loosing, and which was not simply given to Peter, but to all the disciples the Lord addressed in Mt. 18:18.
And the "keys" are manifestly the gospel of salvation, by faith in which the believer is translated into the kingdom of Christ.
"Who hath delivered us from the power of darkness, and hath translated us into the kingdom of his dear Son:" (Colossians 1:13)
Peter was the first to use them in Acts 2, while Paul was the chief evangelist, theologian, and writer, whom your pope reportedly said laid down the cornerstones of the Christian faith and creed.
Peter's keys are no longer used. Mary nor a pope were ever behind the gate Peter's keys opened, for starters. This world is going to .ell in a hand basket so the Catholics are not alone in cutting new keys. As it was foretold would 'need be', by Christ Himself.