Under ROC law, all PRC nationals (including HKers) are ROC nationals. So Taiwan already technically recognises Hong Kong nationals as its citizens.

However, ROC law distinguishes its nationals into two classes – those with legal residence (household registration) in the area under ROC government control (the "Free Territory"), and those without. ROC nationals without legal residence in government-controlled territory lack residence and political rights in Taiwan. However, they can apply to ROC government Immigration Department to immigrate to Taiwan, and if approved, can then apply for full permanent residence and political rights after a period of temporary residence in Taiwan.