Saddam was paid (in chemical weapons, but not only) by the US to invade Iran, it didn't work well for them at the time, despite the MEK helping them with hidden routes and a lot of local support they don't have anymore. The current Iraki leadership isn't stable enough to do the same anyway.

Afghanistan and Pakistan are in a small war that will have some impact on Baluchistan, but official Pakistani ground troops are a no-no, because it will leave ground for the Taliban. Also India invested a lot in Baluchistan biggest port, and Pakistan threatening their investments will probably have them react (India love nothing more than helping Pakistan adversaries). Koweït is too small, Irak Kurds need to secure their autonomous region, and US promised are worth basically nothing. Azerbaijan used Iranian drones and artillery against Armenia like 2 years ago (maybe 3), and Iran apologised publicly after sending a missile to them.

All of this to say: only the US have the manpower and will for a ground invasion.

Probably scale, a few million jews, arabs - qataris and emirates and saudi royalty is unlikely enough to deconstruct Iran, unlike Germany vs multiple comparably or larger sized regional peers.

Iran is 100m large country + 100s millions more shia core / axis of resistance supressed by small regional satraps empowered by outside forces. There are simply 10x more Muslims in region suppressed for decades under same framework where arc of history would would look kindly on Iran+co for destroying US influence and the greater Israeli project and look poorly upon satraps and compradors for failing their spiritual and moral duty of reclaiming the levant. The Nuremburg trials will be reserved for those who failed Islam for secular glitz and kindly on those who protected the faith. Iran simply has the size and spiritual/historic/civilization mandate to win the regional narrative and "moral" war versus gulf monarchs that choose to coexist with Israel. Gulf monarchs who are btw also definitionally autocrats whose contract to bribe populous with petro state proceeds goes away if this war drags on, of all autocrats they are the most likely to fall and least likely to normalize against autocrat regime change. This not to say Iran is "correct/moral" just they have scale and discourse legitimacy Germany didn't.