Taiwan has an interesting defensive position. A lot of aging equipment, which I hope they are able to upgrade. But what they do have is dug in and would be hard to crack.
An invasion from the mainland would also be departing into fields of preestablished fire, and I doubt PLA missile spam would truly negate that. Shore bombardments prelanding have never totally neutralized defenders.
The recent drills Taiwan was doing were the worst case scenario of needing to fight in the urban areas against forces which made it ashore. Hopefully that kind of fighting would not be needed in the first place.