The PRC is not militarily ready for a war against Taiwan. In contrast to the Russians who prepared for a long time on how to invade Ukraine and how to deal with the subsequent economic sanctions that were imposed on them. Probably China will be ready by 2024 to launch an invasion of Taiwan, but even by then Taiwan will have bolstered their defences and military capabilities.
As for the likelihood of the US extending direct support for the Taiwanese, I personally don't consider it seriously. I think at the most they'll just supply them with weapons and not engage their own forces.