Taiwan's independence is de facto recognized by the US and many (most?) other major powers, it's just not recognized de jure because of the PRC's diplomatic policy. For instance, the US basically has an embassy in Taiwan (they just don't call it one), which is staffed by State Department diplomats (who take a leave of absence to work there so they're not technically diplomats when there). It walks like a duck, it talks like a duck, but many have agreed to pretend it's not a duck for reasons.
This stuff isn't as black and white as you seem to think it is.
I'd say that puts it above many countries that might have wide de jure recognition, but limited, ineffective, or largely chilled diplomatic relations, like North Korea.
Declaring isn't the thing that is important.
As I said before, the important part is controlling your own borders, taxing your own people, and having your own military.
That is what makes a country a country. Not things like "declaring" or "recognition".
You can go to a no-man island and declare your own independence and nobody will care about it.
However, a country that interact with other countries, their independence is recognized by both parties.
Further, as Taiwan is so close to mainland, whether geo-politically, or economically, made it detaching links to China infeasible.