It would be very bad for both sides actually, and it will be a war of attrition that I don't know if we have the will to outlast them.
If China was to cut off all the products & materials we get from them or companies around the world they control as well as we aren't getting anything out of Taiwan while there is a hot shooting war, it would cripple our entire economy and supply chain and the corporations and rich elites would be beating down the door of the politicians to order them to give the Chinese what they want so the rich can get back to getting rich.
We however are also one of the biggest purchasers of Chinese products and a huge part of their economy revolves around making stuff or providing stuff we buy. Without us, millions of workers don't have anything to do as the factories stand idle and foreign exchange comes to a halt. That's never a good recipe for maintaining control of your society.
But I think where this will differ from the whole little Russia / Ukraine flare up, is that the Chinese government can't afford setbacks losses or being humiliated, If they choose to go in, it will be an issue where they would most likely prefer to nuke Taiwan and everything around it than lose and that threshold would come up pretty quickly IF our politicians actually decided to go full on fight.
There is a lot for both sides to lose so I don't think the Chinese are in a hurry to kick it off until they think it's in their best interest to do so.