... Taiwan is basically a rebel country which wasn't recognized by the UN for a long time, they split from China and China has always wanted to "reunite the country" (Hitler used this tactic early in WW2 as German land was split post WW1). ...
I'm not disagreeing with you on the rest of your post, but these points are fairly inaccurate.
Taiwan is not a rebel country or a "renegade province" like China wants everyone to see it (and bribed lots of small countries and organizations to support that view in the UN), but rather an independent country in it's own right which was occupied by the Kuomintang forces after they lost the Chinese civil war.
At that point Taiwan was still officially under Japanese sovereignty (until the Treaty of San Francisco took effect in 1952). The Empire of Japan had won the island "fair and square" in the Sino-Japanese war but lost it again in the aftermath of WWII. China itself had only annexed the island in the late 17th century, so it's hardly native Chinese territory to begin with.
My wife's family is native Taiwanese and the natives hated Chiang Kai-shek's brutal occupation force (see White Terror) more than the Japanese.
The reason that Taiwan didn't become an independent country like East and West Germany or North and South Korea is Chiang Kai-shek's idiotic refusal of a two-state solution offered to him by the US at the time the UN was recognizing the PRC as the "rightful" claimant to the Chinese UN seat. Old and senile then, he rather wanted to maintain his claim on all of China and still had delusions of a successful invasion of the mainland.
Back then China would have had no means to prevent Taiwan's independence but today it would likely mean war.
As for our glorious (or rather idiotic and foolish) "leader" Adolf Hitler (democratically elected! - so much for the value of that) - he did use a whole host of reasons to annex neighboring countries or wage war, but reuniting the country wasn't one of them (unless you meant the Austrian "Heim ins Reich" Annexation, though that "split" was over a century earlier when Napoleon dissolved the Holy Roman Empire in 1806). The most popular reason was to protect "German minorities" in other countries (Czechoslovakia) (the "democratically elected" Russian tyrant Putin is copying that approach right now with some success in Ukraine), or defending Germany against orchestrated (fake) attacks (from Poland). He also used a (fake) coup to take over total power over the Nazi party and country (right now somewhat copied by Erdogan, another "democratically elected" tyrant).
Germany was only split after WWII.
After WWI it lost some territory to the newly recreated Poland which caused Eastern Prussia to become an exclave separated from the mainland (kind of like Alaska), but it was not "divided" or "split".
... Of course America supports Taiwan.. And an Attack of Taiwan is an attack on America. ...
I really hope so, but that may depend on who is the next leader of the US.
Any signs of isolationism and not being willing to protect allies at all cost in the event of a Chinese (or Russian) invasion may just trigger such.
