And yet Boeing complain about Airbus being subsided ?
Many parts of an airliner these days aren’t specific to a single type or would need minor modifications, engines, APU, brakes, FMS, AVIONICS, cabin interiors, galleys, lavatories etc can easily be outsourced. The fuselage, wings and tail you need your own design for but I doubt anyone would be wanting to copy too much of the B737 design given its age and recent record.
Back in the 1960s, virtually ever British car manufacturer had its bodies made by a company called “Pressed Steel”, this was bought by the British Motor Corporation which then had all its rivals secrets.