Ofcourse they did, they essentially blackmailed the US and others from "doing Iran style Bunker busting" on its nuke program by using its massive artillery capability against Seoul.
If Japan tries to develop Nukes in the future and Japan already has thousands of hypersonic missiles deployed against China, then it is essentially blackmailing China from not trying to militarily stop Japan.
China will have to weigh the cost of thousands of Japanese missiles coming against Chinese cities and destroying valuable assets vs Going after Japanese nuke program.
China's military intervention against Japan will not be cost free, there will be huge destruction inside China as well. So, it will require enormous level of guts for whoever is Chinese leader at the time to pull the trigger against Japan.
I am afraid China will not be able to subdue Japan without going to a costly war and it cannot allow Japan to develop nukes which will be even more costly. Cause Japan is suicidal enough to launch Nukes against China even if it means its own destruction. They are the inventors of Kamikaze attacks.
I think China needs to prepare to go to war against Japan in the next 10 years.
I doubt Japan has a load hypersonic missile yet but even then, Japanese cities would have to deal with dozen of thousands Chinese missiles targeting military, power, nuclear plants, nuclear weapon stockpiles, industry, universities and economic targets in a area that is many many times smaller than China, pretty easy target.
At the end of the day war sum up as if the sacrifice is worth it and in the case nuclear weapons Japan would have to decide if sacrificing Tokyo and a million of people who live there is a worthy price for a capital that is just 100 km from the Chinese coast.
My guess is that they will conclude that sacrificing Tokyo for Taipei is not worth it. The Japanese warmongers right wingers are opportunistic but I don´t think they are that stupid.