It's a double negative. If nobody will not use them then somebody will

Jokes aside, I'm not sure if Putin is completely sane. He uses nuclear arsenal as a deterrent saying that if attacked he will use them, but at the same time attacks other countries hoping that they won't. I'm also pretty sure that Ukrainians would nuke Russia if they had access to nukes, the same way that Palestinians would nuke Israel.
Knowing that, I think it's not a question if but when.

Take your idea of a war with NATO. NATO is much stronger than Russia, even if Russia was using Chinese weapons. It could prolong the war, but it wouldn't win it, mainly due to untrained army that would have to fight well trained artillery and tank crews from Germany, France and Sweden. Russia sends convicts to Ukraine because that's all they can do without weakening their borders. They expected a war that would last weeks and it's been years. What would happen if they started a war and lost it? Do you think NATO would push them back to the border and stop there? Defeated Russia might try to cover their escape with nuclear weapons.