The Ukraine war has demonstrated you don’t need parity in shells. A dozen or two HIMARS turned the tide against hundreds of artillery pieces; mobility, range, and accuracy mattered more than being able to send hundreds of shells in a general direction.

While we’re comparing Ukraine and Taiwan, Taiwan has significant defensive advantages; tougher terrain, no land border, and they’ve been fortifying for decades. Even river crossings in Ukraine are fraught with peril, let alone an ocean strait.