I’m not a prepper, by the way, but I do keep a few extra necessities and learn and experiment with low technologies (like car repair, building construction and others). Fallout shelter design and building are also interesting.
People think radioactive fallout is this glowing, penetrating, x-ray like thing that's going to get them no matter what, and that belief came from old Cold War era books and movies with half the country physically destroyed due to MAD, mutually assured destruction.
But, with a limited exchange, fallout is going to be dust particles for any downwind who weren't in the blast zone. Ad hoc preparation for that could be as simple as sealing windows and doors with tape and cutting off any exterior ventilation for a week. Even putting damp cloth over openings in walls would be fairly effective.
People forget just how many survived Hiroshima and Nagasaki, that were fairly thoroughly exposed to radioactive fallout with no clue how to protect themselves from it, really no understanding that the threat even existed. Increased birth defects and cancers were the price paid, but life went on.
Making it sound so utterly catastrophic that no one would even consider the possibility was part of an overall strategy to prevent a nuclear exchange from ever happening. It worked when major parties to any possible exchange were largely rational.
They're not rational any longer.
A simple cardboard and foil solar oven is good have around.