“Thus, Europe should continue to buy a lot of other stuff from America, but not the F-35.”
In a war you need more than one type.
It is unreasonable to believe you will only fight a defensive war.
If Europe were ever to strike first, it would only be within a preemptive framework. A preemptive strike is a form of self-defense.
Europe would never invade Russia with ground troops to expand its territory. Unlike Russia, Europe is not an imperial, expansionist entity.
Striking Russian forces while they are massing along EU borders in preparation for an invasion would therefore be a logical and defensive move. Such an action would rely primarily on missiles and heavy artillery; aircraft would not be essential at that initial stage.
Jets would become necessary later, once active frontlines emerge and for precision strikes and special operations.
The immediate future is drones though.
https://news.sky.com/story/eu-warns-europe-must-start-building-millions-of-drones-to-defend-itself-against-possible-russian-attacks-13388472