I suggest you may want to learn about the 2nd exodus, it will alter your understandingI have an idea of what the third heaven is, but I do not know exactly. Nevertheless, heaven would be a reward after mortality. So, some may go to heaven in a third category, after resurrection, as heavenly rewards go. Or to the first or second, etc.
Nevertheless, the rapture does not end in a reward, but protection, as the earth is being burned and renewed. That is, if heaven is a metaphor for the earth, then the reward is the earth for those resurrected from the dead. And the earth is the location for those raptured from mortality so that they can continue to live in mortality in the 1,000 years.
Isaiah 11
11 And it shall come to pass ----- “in that day”, [that] --- the Lord shall set his hand again ---- the second time ---to recover the remnant of his people, which shall be left, from Assyria, and from Egypt, and from Pathros, and from Cush, and from Elam, and from Shinar, and from Hamath, and from the islands of the sea.
Jeremiah 16: 14 - 15
14 Therefore, behold, the days come, saith the LORD, ----that it shall - --- no more be said, ---The LORD liveth, ---- --- that brought up the children of Israel out of the land of Egypt;
15 But, -- The LORD liveth, -------that brought up the children of Israel from the land of the north, and from all the lands whither He had driven them: --------and I will bring them ---“again”--- into their land that I gave unto their fathers.
Jeremiah 23: 7, 8
7 Therefore, behold, the days come, saith the LORD, that they shall no more say, The LORD liveth, which brought up the children of Israel out of the land of Egypt;
8 But, --- The LORD liveth, which brought up and which led ---the seed --- of the house of Israel ---out of the north country, and from all countries whither I had driven them; and they shall dwell in their own land.