ONLY A FOOL WOULD TRY IT!
Take your pick for a ground invasion of Iran:
Amphibious assault from the south -- through waters mined to fuck, with trillions of missiles aimed at them, followed immediately by a wall of mountains where two battalions can hold off an entire corps at the narrow passes.
The Kermanshah corridor from the west, that's how Saddam invaded Iran; he made it a whopping 50 kilometers before getting completely bogged down for 8 years. Again, mountains, the Zargos, then another 500 kilometers to Tehran through mountainous terrain. Plus, you know, Shiites live there, all the pro-Iranian Iraqi militias, and the current Iraqi government would never in a million years allow it.
Khuzestan may look promising with how close it is to Kuwait and the Arab minority living there and all that, but, again, you'll run into the Saddam problem.
Azerbaijan, from the north. No port infrastructure, no rail link with NATO, few military airfields. And again, damn mountains. A thousand kilometers through mountainous terrain that includes passes over Damavand, the highest mountain in the Middle East. And even then, the Kremlin, liberals as they may be, still wouldn't allow that. Also, Iran can easily go beast mode and destroy the oil infrastructure in Azerbaijan with a few dozen drones, wiping out 2/3 of the Azeri economy.
Turkmenistan, the northeast. 1,000km across desert with no supply lines whatsoever. Then more mountains. Also the political problem.
Pakistan, the southeast. Fifteen hundred kilometers through a region with zero infrastructure, just desert, fuck-all nothing, and then you run into... yeah you guessed it, mountains. And of course Pakistan would never allow it.
The only RELATIVELY viable option in terms of geography and logistics is Turkey, but the Turks aren't idiots either and don't want to get involved with this.