Basically a good rundown... but let's look further.The first time Jesus speaks in the first person in this book is in Re 1:11, we learn this because the speaker both John and the speaker identify him in the following verses.
Let's read Re 1:4,5a together, please.
John to the seven congregations that are in the province of Asia: May you have undeserved kindness and peace from "the One who is and who was and who is coming" (the one mentioned in vs 8) and from the seven spirits (Re 4:5) that are before his throne, and from Jesus Christ, "the Faithful Witness," (Re 3:14) "the firstborn from the dead," (Col 1:18) and "the Ruler of the kings of the earth." (Ps 89:27; 1 Tim 6:15)
Verse 7 continues about Jesus, "Look! He is coming...." It does not say, "I am coming." John is still writing
I can not see how the sentence fragment "is to come" or "who is coming" in verse 8 defines the speaker as Jesus. This fragment in its entirety is "the One who is and who was and who is coming, the Almighty." Does that not remind us of this passage?
Before the mountains were born
Or you brought forth the earth and the productive land,
From everlasting to everlasting, you are God.
- Psalm 90:2
2Who bare record of the word of God, and of the testimony of Jesus Christ,and of all things that he saw
7 Behold , he cometh with clouds; and every eye shall see him, and they also which pierced him: and all kindreds of the earth shall wail because of him. Even so, Amen.
Up to here, John is speaking and, as we can see, it is all about Jesus.
Now we have a change of tone:
8 I am Alpha and Omega, the beginning and the ending, saith the Lord, which is, and which was, and which is to come, the Almighty.
Obviously, this isn't speaking about John. Up until now, it has all been about Jesus and vs 9 continues about Jesus.
We know that John isn't the Alpha and Omega. We know that the Jesus does have the designation as Lord.
We also understand according to 22:20 He which testifieth these things saith, Surely I come quickly. Amen. Even so, come, Lord Jesus" it is the Lord Jesus who is to come. Simple application of logic brings us to the reality that the one who was, and is, and is to come is Jesus, the Alpha and the Omega.