To clarify, 3166-1 is for countries, dependent territories (i.e. Guam), special areas (Taiwan, Hong Kong) i.e. TW gets a flag being in 3166-1 list but under UN resolution 2758, PRC gets to subsume TW as special area - "Taiwan (Province of China)". 3166-2 is for subdivisions (TW provinces, UNDER CHINA), i.e. all TW provinces are considered subdivisions of China/PRC. Same with HK. Unicode doesn't offer opinion in the sense the opinion is whatever UN recognize as countries, which will never include TW as long as PRC holds P5 veto.

In the meantime this arrangement works out since ROC constitution still legally asserts it's but part of One China polity, i.e. it doesn't matter what TWers think or DPP claims, or tries to legally engineer (additional articles /legal fiction limiting ROC political jurisdiction to "free area" of tw + islands). Until TW voters&politicians actually formally separates / declares independence, as in change ROC constitution by renounce claims on mainland, they'll lose 3166-1 designation because PRC gets to remove them, and won't get a new one because PRC veto. They'll lose their emojis (maybe iso codes, maybe domain depending on US/ICANN drama)... which TBH will be least of their worries.

Almost nobody in Taiwan would call it a "province of China" (some would if you redefine what China means, ie not PRC). But as usual standards bodies bend to whoever has power at the moment.