Material aside, without know how, you can never develop any turbofan engine, period.
No nation will provide you the core part, and even if they do, they will not give you the source code and you are left with junk that you have no idea what it can do or cannot.
There's no shortcut. State's capability to develop own source code, materials, design of the core of tubofan engine etc will all be put into test, and until one has been rolled out successfully, any timeline promised should be taken with a grain of salt.
No nation will provide you the core part, and even if they do, they will not give you the source code and you are left with junk that you have no idea what it can do or cannot.
There's no shortcut. State's capability to develop own source code, materials, design of the core of tubofan engine etc will all be put into test, and until one has been rolled out successfully, any timeline promised should be taken with a grain of salt.