I suppose any afterburning turbofan engine will do if it fits? Again, not particularly opinionated. Just get out from under US control using the path of least resistance.
The Chinese have been trying for years to reverse engineer older Russian turbofan engines and still can't get them quite right. And those are a level below the F414 in complexity.
(Then just make sure not to hook it up to any radio transmitter under the engine's direct control, so it can't call home to the American manufacturer and be disabled remotely.)
Patriot systems were in use to shield Kyiv et al to great success.
I know it sucks to hear this, but if the US goes isolationist, there's not much anyone can do.
As for Ukraine, they have the S-300 ABM, the Buks and Osa-AKM for air defence. (The Russian made Buk was one of the first systems able to intercept cruise missiles and US-made Lance tactical ballistic missiles, Harm anti-radar missiles and other airborne and ground-based precision weapons). Though quite old, they are still formidable and is one of the main reasons Russian Air Force has a low key role in the current ongoing conflict. (That + the NATO AWACS).
The problem Ukraine had was that they ran out of missiles for these platform and that's why the US provided them with the Patriot system. But since America did not have enough spare Patriot missiles, East Europe and the US also modified the Buk platform to fire the radar-guided AIM-7 Sparrow and the semi-active radar-guided RIM-7 Sea Sparrow, as well as the heat-seeking AIM-9M Sidewinder air-to-air missile.
