If the EU can't rely on Nvidia everything must have broken down already, no advanced semiconductor today could be produced by one country only. Unless there's some alternative to ASML and Zeiss the EU is part of that chain.
That's why this talk of independence is unrealistic.
No, just really hard. Tackling one problem and thinking it done is the same error as taking one step and thinking you've climbed Mount Everest; the converse is the same, just as one cannot climb Mount Everest without the first step, one also cannot become independent without making the first independent replacement for one the links in the chain you rely on.