The current rule is that if there are direct flights from your departure country to China, then you have to take that. Otherwise you won't get a green code. For this purpose, the Delta, UA, and AA flights that stop briefly at ICN are eligible (ICN is not really seen as a stop).

As a Chinese citizen you CAN transfer through Taiwan (https://www.roc-taiwan.org/pl/post/3354.html) but the airline won't let you board in the US because the Chinese consulate / embassy won't issue you a green code because of the above rule.

There are other ways, such as staying for 30 days in Korea or Thailand. Flights from Thailand to China or super expensive now though.

These questions are probably better discussed on the other thread, Current China Entry Policy