There is a lesson in Ukraine and Iran being that invading a prepared country isn't easy and takes full commitment. Taiwan is most likely very prepared to defend itself.

It might be prepared, but opportunity like that doesn’t present itself very often. Both US and Russia are tied in huge wars and won’t have spare capacity to answer Chinese aggression.

One thing to note, is that Ukraine has received billions of dollars of aid from EU and United States.

I'm not sure if the West has that kind of cash to dish out after the current war with IRAN.