Ukraine is a seasoned turbofan producer (albeit for very small or large aircraft), would it be out of the realm of possibility to see them develop a turbofan for a fighter if asked and paid to do so? It's no immediate option by any means, but if put in the pipeline, PAF could potentially get it in 10-15 years.
All of Ukraine's turbo fan's capability lies within Motor Sich, part of the Motor group. Within the Soviet Union, Motor Sich used to co-produce the turbo fans, turbo props, and turbo jets for the Soviet empire. This capability is now limited to simply producing what they know, and nothing new is getting developed.
Their overhaul capability for fast jets is limited to the Motor plant, which overhauls RD-33-2 and and AL31F engines. They have a lot of indigenous capability but don't product any capital parts or what we call "Aggregates" such as fuel control units, DEC, gear box etc, only repair them as per procedures from OEM of these engines. They have no authorisation to assist Pakistan on RD-93 overhaul, though they have been helping CATIC quietly over many years with engine overhaul capability.
Designing a new engine is a far shot for them, and the Chinese are much further ahead this route. If PaK AF gets desperate and follows this route, it would not be Ukraine.
Most important, it dont smoke and 10% is consider a massive increase. F-119 is also considered new compare to F-100 engine, doesnt that mean it shouldn't be used for F-22?
Comparing Chinese developments with US developments is an unfair argument. However, Pakistan is a seasoned users of Chinese engines, copies of Russian engines, both on the licensed produced Mig 17, Mig 19, A5, and Mig 21 variants. On paper, the WS13 looks good, but I am sure the decision makers in Pakistan have a lot more data at hand to decide the future of propulsion for FC-1.
