This is a clear tell that your knowledge of the situation is basically just Wikipedia plus media reporting. Approximately nobody in Taiwan views it that way. It is an obscure legal fiction of no relevance. It only persists because of a red line drawn by the PRC.

It’s kind of like how New Zealand is included as a province of Australia, technically, in their constitution.

I didn't saw anything about how people view this? As you state, it's a legal fiction, but it's quite useful in numerous contexts like this, because it lets Unicode de facto include the Taiwan flag without actually including the Taiwan flag.