Firstly, Ukraine’s land area is 600k km2 and Taiwan’s is 36k km2. That is not 1/3rd the land area, but 1/17th. Secondly the actual land area of concern for Taiwan in an invasion is much smaller than 36k km2. Only maybe 1/4th of the island is populated, and nearly all that populated area is flat terrain directly next to the coast facing mainland China. 3/4th of the landscape is high grade mountainous terrain that isn’t populated and not amendable to tanks anyways. It doesn’t matter how many ground forces Taiwan has when the inherent geography forces the ROCA to funnel its massed infantry in very specific spots if they want to defend the territory that matters, which is not in fact the whole island.
This exposes them to suppression and attrition by air. In an ideal scenario where PLA air power has swept clear of the landing zones and most likely defensive outposts, mechanized amphibious assault groups are still necessary precaution for any resistance that might break through, and to form a secure beachhead to begin massing forces as quickly as possible to press advantage. This is just basic good form if your goal is to try to attain an overwhelming victory to end the conflict as quickly as possible. The point of the amphibious landing and ground forces here isn’t to take the lead in the attrition fight, but to take and hold positions after area has already been cleared. The main point here is that the PLA isn’t depending on ground maneuver for its primary offensive push.
Even if the ROCA retreats to try to reform defensive lines further back or in urban areas, ceding the coast means ceding the ports, and ceding the ports means ceding supply lines for an island that is already dependent on sea traffic for 90% of its energy and 70% of its food. An urban retreat just means the roads to sustain ROCA supply lines get cut. If the ROCA wants to retreat all the way into the mountains they can enjoy trying to stay relevant and fed as they’re starved out while populated areas get fortified against their re-entry. You are fetishizing attritional ground fighting while sidestepping the much broader and better strategic options China has against Taiwan given the PLA’s current capabilities.
You should study the map closer and think through what kinds of fighting will actually happen and where on the map they will actually happen in if you want to sound like you know what you’re talking about. And if you don’t bother to get even these basic details right you are indeed the wrong person to ask.
To your knowledge, outside of amphibious landing training, what exactly about the PLA’s training for Taiwan scenarios have you observed that would suggest to you they plan to primarily prosecute this war by ground maneuver? This is an important question if you’re going to make references to “the way staff work is performed” since for the last 30 years the vast vast majority of investments the PLA has made specifically to prosecute a war with Taiwan has not been on ground maneuver capabilities but on the air sea fight.
You talk as if PLA ground forces have to contend with the ROCA while the ROCA can just shrug and ignore the PLA’s air power. This is one of the problems with trying to analogize China with Russia. How Russia employed air power in its war with Ukraine is not how China is training to employ air power in Taiwan. Russia’s air employment doctrine is severely underdeveloped relative to China’s, so what Taiwan faces here is not determinable by observing how fighting looks between Ukraine and Russia. China’s able to field far more persistent and denser air cover against a much smaller area against Taiwan than Russia will ever be able to do against Ukraine.
Ukraine also has access to unassailable supply lines because it’s connected directly to Western Europe, a flank that Russia has no way of reaching. The ROCA’s ability to “prepare and react” is meanwhile dependent on securing supply lines by port, ports that will be immediately lost to them if they lose the landing fight. Once again please study the specifics of the China Taiwan scenario rather than draw poorly studied analogies.