Manufacturing the processor itself is different issue from what architecture that processor will be. If Europe produces any consumer processors like that it wont be x86. It will be Risc-V (maybe arm? its UK but owned by Softbank so nope)

Just because SoftBank own it now, do you really think if Europe went to it and said "can we buy half, if so we'll buy $X amount of licences otherwise we'll start (effectively) a serious competitor in risc-v.

Again why to fight for ARM where Softbank will want a huge payoff. When you can instead put this money into RISC-V. I guess i am comming from viewpoint that what EU really needs are independent chips that don't have to be the most cutting edge. I think performance few years behind is fine for majority of needs and that would make europe much more independent. So chips for AI no but for everything else it would be a great start.

Most of the machines for the rest of the process also come out of Europe. Building the factories wouldn't be all that hard. Actually developing and running a full production sub-10nm process is a different beast entirely.