Does the USA recognize Taiwan as a sovereign state? No.
Does the PRC recognize Taiwan as a sovereign state? No.
Does Taiwan recognize itself as a sovereign state separate from mainland China? No.
Does the USA recognize Taiwan as a sovereign state? No.
Does the PRC recognize Taiwan as a sovereign state? No.
Does Taiwan recognize itself as a sovereign state separate from mainland China? No.
The only body that makes decisions about Taiwan is the Taiwanese government. It has 100% control of the land within its borders.
Not sure how much more sovereign you can get than that.
Being that the Taiwanese government claims Beijing and Shanghai as being within its borders, I don't think that this is the case.
It’s a sovereign state with claims over a larger territory than it controls.
The Republic of China (Taiwan) is not going to say that China is separate from china. Their position is that Taiwan is the rightful ruler of mainland china (currently controlled by the communist party).