The distances inside China are what the B-737, Airbus-320 and C-919 are designed for
A CR-929 is designed for longer distances up to 12,000km so China needs other countries to accept the CR-929
both A320 and B737 were designed pre open China there modernized iterations were designed for general aviation and
Not for purely domestic Chinese flights.
These planes are designed for longer distances, which means foreign acceptance is required
modern narrows like the MAX and Neos are capable of both Transatlantic and Transpacific flights with limitations based on configuration, model, passenger load and origin destination. These still leads to a preference to larger liners like the A321XLR and B757.
Generally builds of airliners optimize performance around the base line middle configuration with shorter and longer versions suffering the trade offs. Some will farther trade passenger cargo capacity for additional fuel tanks to increase range.
I don’t see the politics as the problem even in the old Cold War Soviet liners were accepted in international flights. The question will be support. If Ryan air gets a fleet of 919s will they be able to maintain that fleet? If Air Mexico buys 929s can they be fixed without shipping back to China? That’s Comac’s biggest point of question. If they can solve that then they can actually stand as a rival to the Duopoly. If they can’t then they end up in the same state as the Soviet liners. Isolated to markets that already had a heavy bias to the combloc