You've probably seen it already but you can read this effortpost by LargePenis about the rise of Shia political islam.

It's important to remember that 60 years ago the situation was the opposite. Iran was a secular comprador state and the biggest ally of America and Israel in the middle east, while the Arab world was unified in opposition to Israel. Most prominently the secular socialist government of Nasser, but also conservative anticommunist Saudi Arabia. During the 70s, after the failure of a strategic defeat of Israel to materialize, some Arab countries started to consider repositioning themselves geopolitically. This was also the time that the US turned the middle east into a cornerstone of their foreign policy with the introduction of the petrodollar. The collapse of the Soviet Union only accelerated the Arab world falling into western orbit with the collapse of progressive secular movements, continuing until today with the fall of Libya and Syria.

Specifically why Sunni political Islam was not able to form a front against Zionism compared to Shia Islam I would guess it's also because of the conditions they developed in. In much of the Islamic world Sunni political islam acted as an opportunistic force of reaction against progressive governments, being sponsored by pro western forces. While in Iran it specifically arose against American-Zionist influence, and in other countries with the additional context of Shia interests being sidelined by the Sunni majority.

Of course reality is more nuanced, other people may correct me