I think we all know this "Third Temple" will be an abomination, probably a five-sided structure with entry portals for the "Five Major World Religions" (since the current narrative is that "we all worship the same god") and then a major central area that recognizes their commonality.

Five-sided ... maybe like the "pentagram"?

The usual and commonly presented narrative is that there is valid worship going on in this temple because the Jews built it and it's a return to the Old Testament sacrificial system, which God will find acceptable.  Then after 3 1/2 years, "The Antichrist" goes into the Holy of Holies, sits down on the Mercy Seat and announces to the world that he is God.  Suddenly the Jews "get it" and see this as the abomination of desolation, and flee Jerusalem.  This is "The Antichrist" allegedly fulfilling Daniel 9:27.

This is incorrect.  Hal Lindsey or someone made this up, but it won't happen that way at all.  Rather, the "worship" in this place will be abominable from its beginning, and the "sacrifices and offerings" will probably include HUMAN sacrifices.  Jesus will return at the end of 3 1/2 years and HE will destroy this so-called "temple" and everything in it.  A tenth of the city will fall and 7,000 people will die.

This is not a mid-week bridge between a 3 1/2 year "tribulation period" and 3 1/2 years of "great tribulation."  The popular evangelical prophecy models have a LOT of problems and this is one of them.

When full-fledged Moloch worship is re-instated on the Temple Mount, God will have raised up His two witnesses to stand before and confront the "god of the earth" (Rev. 11:4).  The gentiles and their evil religious system lasts 42 months.  The two witnesses prophesy 1,260 days.  Then it's end-game.

We'll watch from the mezzanine.  The reason I'm writing is because evangelical Christians have been sucked into financially supporting the Jews and the construction of their "Third Temple."  We've been told by many of our pro-Zionist "Christian Leaders" that this is a God-thing, that God wants His Jewish people to rebuild a temple in Jerusalem.  This is not true.  Any money collected will be used to build an abomination.