IIRC, Helms-Burton only applies to Cuba, not Saudi Arabia, Iran, Iraq, or Mexico.
I know that. That is why I urged Trump to let ExxonMobil go after their other nationalized interests. You are correct though that that might indeed require some legislation similar to Helms-Burton.
I see on further checking that Hitler’s Germany became a big purchaser of the then nationalized Mexican oil, and that the US then ultimately pressured Mexico into compensating the US oil companies at at least a pittance for their lost property.
I strongly doubt that Trump would go after the other countries for compensation to US companies for their nationalized oil interests, even socialist Venezuela. The value of the nationalized properties in those other countries was/is huge. For example, some put the current value of Saudi Aramco (the Saudi state-owned oil company) at 2 trillion, much of it the former property of Aramco (the Arabian American Oil Company which became a partnership operation of various private oil companies).