We know that Paul was stoned at Lystra. While there is not agreement on whether of not he was actually dead I think he was. Consider Paul’s writing in 2Cor 12 1-4. Being directed by the Holy Spirit with his writing, he was not allowed to say he was the one who went and saw heaven. It is usually accepted that it was in fact Paul. Further support is given in 2Cor 5 6-8 - especially verse 8. Why was Paul " confident " that absent from the body is to be present with the Lord? Because he had already been there where the Lord is.
Moving from the 2 Cor 12 verses to Hebrews 12 22-24. I submit that the author of Hebrew was Paul and that he hid his authorship because he revealed what he had seen and heard what is referenced in 2 Cor 12 1-4. It was necessary to hide himself as the author else he become puffed up with pride and so forth. It was needful that the information in both passages come out and just as necessary that Paul stay humble.
Paul actually saw the places mentioned in the Hebrews passage and heard what the living beings said and sang. The critical part of this passage for what I write is the last part of verse 23. "...and to the spirits of just men made perfect." These " spirits of just men" are humans that have died and are now in heaven. They worship the Father because they can see Him as He is.
It is important to now that in verse 22 the verb is present tense. We are already there in the spirit.
Based on the Hebrews scriptures, there is a place in our worship here on this earth where our worship mixes to a point that the realized presence of the Father flows from His throne down to and through us if we are in tune / harmony with those 'perfect spirits'. That flow of love, joy, peace might not be as strong as what is going on in heaven yet it much stronger than what we usually have in churches today.