Let’s say “Mr. Michael Corbin” decides to visit Taipei. He doesn’t need a visa
since he’s a US citizen. He spends a few days in Taipei and then flies to Kinmen
on a domestic flight. Will he be allowed to travel directly from Kinmen to
China? (the short boat trips that Taiwanese businessmen take between the
two places) Mr. Corbin does have a valid/current visa for China.
Thanks for your help! 
No.
yeah… I just found the answer myself…
I guess the only option is those nonstop charter flights between China and Taiwan.
My co-worker took one of those flights when they allowed ADAs to fly on them… 
You can take a normal flight with stop-over in Hong Kong, Macau or Korea. I heard some of them just touch down, wait for a few minutes on the runway and then take off again though I am not sure which airlines and if that’s a permanent thing or still done.