At least some work must have started and project must be funded and on track. It must connect the main body of asia in the mainland PRC as of 2023 to the main land of Taiwan island. Multi-step is okay as long as it's all connected via a bridge. For example, Mainland => Kinmen County => A small island near Taiwan => Taiwan main island would count.

You'll be able to travel above water not flying between the countries i.e. it's not a tunnel.