No time like the present to get involved with something like a Community Emergency Response Team or its local equivalent. FEMA has manuals and other training materials available online which address the matter of chemical, biological, radiological, nuclear and explosive (CBRNE; sometimes just CBRN or NBC depending on agency or publication date) incidents. Won’t make you an expert on yield estimation or fallout mapping but there is information which may be useful for improving individual and community resilience.
Personally, I think the likelihood of getting nuked is low and it’s much more likely that a CERT volunteer will be called upon to assist in natural disasters or major accidents to relieve the burden on professional crews. Where I live, teams have been employed to assist in redirecting traffic around areas with downed power lines or, in one case somewhat recently, a significant natural gas leak. Firefighters and other specialists establish a safe perimeter before handing off the site to volunteers so they can respond to other incidents throughout the city while repair crews work down their list of priorities.
Long comment short: building useful skills and relationships before shit meets fan means less scrambling to figure it out on that day and there are real, practical applications for that knowledge beyond LARPing with Jim-Bob’s moron militia.