There are millions of U.S. cluster artillery shells available in Turkey, too.
An examination of the data says S. Korea has in storage about 3.5 million unguided / conventional artillery shells of its own. This is after having provided 500,000 such to the US on a loan agreement for transfer to Ukraine in 2023. No doubt consumed by now.
Of the 3.5 million, about 200 are guided. They are nearly all of the old, unguided types. S. Korea has other artillery shells that they self-manufactured and are modern and guided, but do not conform to 105mm and 155mm NATO standards for the cannons themselves.
Not an artillery expert. That’s all from AI’s web search much faster than I could.