You had separated the two in your argument, so I focused on the fertilizer aspect which you had indicated as the most impactful. Regarding LNG, all of the countries combined that could be impacted by the strait's closure would only just pass Iran itself to hit the #3 spot, and that's mostly from Qatar and Saudi Arabia.

All of them combined, including Iran, produce less than Russia alone, and nowhere close to the US. It's not so much that there will be shortages due to lack of supply, there will be shortages because it will get so expensive that poorer countries won't be able to afford it.

Or they start trading with Russia, giving them more funds for their invasion of Ukraine.

https://en.wikipedia.org/wiki/List_of_countries_by_natural_gas_production