Do you know how to build a nuke? You might know the technicaly details of how a nuke is made, but do you know everything that's required, all the parameters and pressure values that are required? I find that unlikely, but AI seems to be increasingly more capable of providing such instructions from cross referenced data.
Even if sources have been lying to me, which is certainly possible, I believe I understand enough to determine cross sections by experiment and from that to determine critical masses; for isotopic enrichment I know about the calutron, which is meh but works and can be designed from scratch with things I know (though caveat have not memorised, just that I know the keywords "proton mass" and "Lorentz force" and what to use them for); for trigger, I would pick a gun-type design rather than implosion, again this is meh but works and is easy.
A few tens of millions of USD mostly spent on electricity, a surprisingly large quantity of natural uranium (because the interesting isotope is a very small percentage), and a few years, and I expect most people on this forum could make a Little Boy type bomb.