Actually Europe would stop supplying components for the F-35's so the US would not be able to build any more or keep the ones they have working, let alone sell them to Russia. Russia would never buy them anyway, how could they trust that the next US president wouldn't pull the plug on spare parts? Would they trust that Trump is going to become dictator for life? (And what happens after he dies?) Russia has their own fighters that may not be quite as capable in some ways, but are good enough. Russia sells jet fighters themselves, they do not buy them.
>Europe is completely reliant on the US and US technology for defense right now, these systems took decades and trillions of dollars to build and refine, and an 800 billion EUR investment does not magically create a military industrial complex overnight.
Europe already has a large local military industrial complex. Half of what Ukraine has received has come from Europe. They would only have to expand what they have, not develop new technologies, except perhaps for a replacement for the Patriot missile system. They'd get a boost from converting their existing factories from building US weapons components to building EU weapons components as well.
I'm actually surprised that the US military industrial complex (MIC) is not screaming bloody murder about some of this. They stand to lose sales of replacement weapons for those sent to Ukraine, to lose support contracts for F-16's, and to lose a whole lot more if the US pulls out of NATO. Even if the US does not pull out of NATO, the NATO countries have already started investing in their own defense industries, which is going to severely cut into US MIC profits. They should be terrified.