There's 100km of sea between Taiwan and China. Not China (nor anyone else) has anything close to the blue water amphibious assault fleet it would take for an effective invasion force to cross it. It would take multiple years to build such a fleet, impossible to hide, and while they built it Taiwan and her allies would assemble the world's largest anti-shipping missile arsenal. I don't want to sound flippant, but I doubt a single ship would make it to within 10km of Taiwan.

Or forget amphibious assault, say China tries to go airborne. An even longer period unmistakably building an unprecedented heavy cargo aircraft fleet. An even longer period for Taiwan and her allies to build her already impressive air defences into an impregnable shield. Again, not a single aircraft makes it even over Taiwan's territorial waters.

The Russian experience has actually been eye-opening, but not in the direction you assumed. Developments in missile technology have totally changed the game. Even today, the vastly superior Russian air force cannot fly over ukrainian territory. The Black Sea Fleet has been driven away - and Ukraine does not even have a navy! And even given their massive advantages in size and military strength, it's far from clear that Russia will prevail - far from it.

No, you can't really compare the two. Russia could always have invaded any of their neighbours if they decided to. China literally can't invade Taiwan, not if you assume even the most basic preparation and competence of herself and her allies. The best they could do is a blockade, and hope for capitulation.

All of this in my own non-professional opinion of course, but I'm not completely uneducated on the topic. There's more - far more - information laying things out much better than I ever could, I encourage anyone overly concerned about an imminent war over Taiwan to seek it out.

It seems missiles don’t solve all the things else there would be an “invasion” on going for 600+ days.

I guess war is harder than Internet comments.