Does no one on this thread think self-sustaining human habitats can’t be built by robots? What about contained local terra-forming? Huge projects, but can be done with current technology. Finance and time are the problem, not the technology. Radiation? Ever hear of Faraday containment? If you have a bird in cage, you already have one. Just surround the transport ships with a Faraday cage system for emp and current systems for cosmic radiation. There’s a reason that the ISS doesn’t kill all the astronauts that have been on board for years.
Seem to recall Van Allen’s belts trap much of the particle radiation? ISS avoids much exposure through location.
Thin metal stops initial particles and produces secondary particles plus X-ray. Thin layers of foil alternating with speciality plastic sheeting performs better as shielding.
New sunblock and internal medication, which combines melanin with selenium, offers another approach to avoiding radiation damage.