RoC only claims that because any deviation from their existing policy is "declaring independence" and what China wants as an excuse to invade and kill millions of people.
That's only true if you take at face value an official lie that absolutely EVERYONE understands to be a lie, as well as understands that everyone else knows it's a lie.
That's like saying North Korea is a democracy because everyone calls it the Democratic People's Republic of Korea.
North Korea is only Democratic because Stalin hated the idea of them being called PRK, which would resolve to the same cyrillic TLA as PRC.
No they don’t. They have a totally obsolete, totally ignored (by the government and everybody else) article in their constitution claiming China, which they can’t remove because the actual China has threatened to immediately invade them if they do.