People fear what might happen if China suddenly blocked all exports to their country, and rightly so. China is a country where the government wields that kind of totalitarian power. However, this hasn't happened even once yet. The Chinese government knows that, once they play that particular card on one nation, every other nation in the world is going to freak out, stop talking about diversifying away from Chinese manufacturing, and actually do it.
The world absolutely should press the Chinese government to behave in an open and responsible manner on COVID and on many other fronts. China will respond with their usual hostage-taking and "wolf warrior" diplomacy, but it's a sham backed by thin air. China needs the world as its customers even more than the world needs cheap Chinese manufacturing. If the world's governments are willing to show a little solidarity then much can be accomplished.