Before or during a war? They won't supply these before the war since the RoC armed forces consider themselves a serious military (cute, I know) and serious militaries buy big ticket items like jets and warships. They're not going to spend an inordinate amount of their budget on guerilla warfare weapons like ATGMs. Furthermore, their sponsors in the US military-industrial complex want to sell the big ticket items.US will for sure 100% supply Javelins, Man pads, ATGMs galore to Taiwan.
During is impossible. Taiwan is an island, there's no way to supply it during PRC military operations. Any plane overflying the island or ship docking not authorized by the PLA is going to get blasted.