And that is particularly true regarding the opening of the Gospel to the Gentiles by Peter at the house of Cornelius. The Gospel that they preached opened the door to the kingdom of heaven to the Gentiles and it remains open to this day.
And there is no evidence that those keys ever left the apostle's hands and were passed on to anyone else, except for the Gospel and their writings.
Pastors in churches all had the Scriptures in their hands which they used to open the door to the kingdom of heaven to all who wanted to enter. Those were the keys and they still are.
To those who claim to some other exclusive set of keys, I ask: Show us. Prove it. Otherwise:
Whoso boasts himself of a false gift is like clouds and wind without rain [Proverbs 17:20].
The Apostles dind't walk around with the Christian bible in their hands. They wrote the New Testament later on. So, what keys were they using then?
The NT says nothing of using the Scriptures as the key to heaven, but it says "whatever you bind shall be bound in heaven, and whatever you loosen shall be loosened in heaven..."