As long as there is any prophecy in Revelation that doesn't have a fulfillment, then we have to say that it will be fulfilled in the future, physically.
The kingdom is spiritual at the present time, but physical in the future. Otherwise, why would there be 2 fulfilments of the creation of a spiritual kingdom?
When talking about the '1000 years' of Rev 20, it just means the Day of the Lord (as per 2 Peter 3:8) which is a deliberately ambiguous amount of time.
Then I saw an angel coming down from heaven, holding in his hand the key to the bottomless pit and a great chain. 2 And he seized the dragon, that ancient serpent, who is the devil and Satan, and bound him for a thousand years,
[Mirrors the 5th Trumpet. literally 1 day, the day that Mystery Babylon receives the wrath of God via the white horseman, Trumpets 1-4, Revelation 18:8. This is the start of the 'is not' phase of Satan, Revelation 17:8.]
3 and threw him into the pit, and shut it and sealed it over him, so that he might not deceive the nations any longer, until the thousand years were ended. After that he must be released for a little while.
[After Mystery Babylon is destroyed in 1 day (Trumpets 1-4), Satan is released at the 3rd woe (7th Trumpet/ 7 bowls of wrath) in the form of the beast from the sea & earth. This 'beast from the abyss' (sea & earth) rises up at the end of the 2 witnesses 1260 days, at the same time as the physical kingdom of God is starting (Revelation 12:10-12). (people think that the 6th bowl war/ 'Armageddon' is 'at the end of 7 years', but in fact, it occurs shortly after what people call the 'mid-point': the signs that the false prophet is performing in Revelation 13:13-15 are the same signs described in Revelation 16:12-16)
4 Then I saw thrones, and seated on them were those to whom the authority to judge was committed. Also I saw the souls of those who had been beheaded for the testimony of Jesus and for the word of God, and those who had not worshiped the beast or its image and had not received its mark on their foreheads or their hands. They came to life and reigned with Christ for a thousand years.
[the 'great tribulation' is strictly the wrath of God. There are 2 places where wrath is given: at the beginning of the Trumpets (upon Mystery Babylon) & at the 7th Trumpet/ 7 bowls of wrath. Immediately prior to Mystery Babylon receiving wrath in Trumpets 1-4 at Revelation 17:1, Christians are warned to come out of her (Revelation 18:4).
Christians are killed by the beast for not taking the mark prior to the wrath/ judgment upon Mystery Babylon (Trumpets 1-4), then the mark & image are offered again at the 3rd woe/ 7th Trumpet. That is what is meant by Revelation 17:8, The beast that you saw was, and is not, and is about to rise from the bottomless abyss and go to destruction. And the dwellers on earth whose names have not been written in the book of life from the foundation of the world will marvel to see the beast, because it was and is not and is to come.
the timing of which is derived from the fact that it is a bowl angel that says this, meaning it was prior to the 7th Trumpet, went away, then comes back at the 7th Trumpet/ 7 bowls of wrath.
5 The rest of the dead did not come to life until the thousand years were ended. This is the first resurrection.
[the '1000 years' is a deliberately ambiguous amount of time that ends when Satan is released from the abyss, ie the 3rd woe, 7th Trumpet/ 7 bowls of wrath. The 'rest of the dead' are surviving Christians who are told to 'come up here' at Revelation 11:12: a symbolic resurrection as in Ezekiel 37:12-28).
Put another way, the 'great multitude' of Revelation 7 (who came out of the great tribulation, Revelation 7:14) is the 1st part of the 1st resurrection, and the 'come up here' of Revelation 11:12 concludes the '1st resurrection'/ at the end of the 2nd woe/ start of the 3rd woe.
6 Blessed and holy is the one who shares in the first resurrection! Over such the second death has no power, but they will be priests of God and of Christ, and they will reign with him for a thousand years.
[All surviving Christians will rule the physical kingdom of God. All martyrs & survivors will not be destroyed in the 2nd death (soul death). Their descendants will be tempted by Satan after a symbolic 1000 physical years.]
7 And when the thousand years are ended, Satan will be released from his prison 8 and will come out to deceive the nations that are at the four corners of the earth, Gog and Magog, to gather them for battle; their number is like the sand of the sea. 9 And they marched up over the broad plain of the earth and surrounded the camp of the saints and the beloved city, but fire came down from heaven and consumed them, 10 and the devil who had deceived them was thrown into the lake of fire and sulfur where the beast and the false prophet were, and they will be tormented day and night forever and ever.
[Satan is released for the 3rd woe for the 6th bowl war/ aka Armageddon. For Christian descendants, 1000 years later.
The 6th Seal, Trumpets 1-4 war is the Gog war that results in Ezekiel's temple.
The false prophet emerges at the end of the 1260 days of the 2 witnesses, then 5 months later is Armageddon when he goes into Ezekiel's Temple and call himself God. (5 months + 7 months cleansing the land Ezekiel 39:12 = year of recompense Isaiah 34:8)
The 6th Bowl war is the Gog war that results in the New Jerusalem with no temple.