We are clearly talking about a planetary-sized magnetic field. But I don't think it's in the realm of impossibility. With a sun-shade like that of JWST, tempera

We are clearly talking about a planetary-sized magnetic field. But I don't think it's in the realm of impossibility. With a sun-shade like that of JWST, temperatures naturally drop to superconducting ranges and at that point a closed electric loop has effectively zero resistance. So, at least in theory, you could induce an infinite current into it, slowly gathering solar energy until you build up the required magnetic field. The limiting factor would be the physical strength of the winding. I don't have the technical expertise to estimate if such a project would require mere billions, or planetary sized piles of money.