[meindnoch]

Using publicly available knowledge won't get you a working nuke, even if you have the necessary fissile material. A lot of finicky details have to be just right in order to get a nuclear explosion instead of a fizzle. C.f. https://en.wikipedia.org/wiki/Fogbank

More often than not, comparatively simple chemical reactions are hard to reproduce reliably just by reading the research papers.

[bitexploder]

I have watched a lot of Nile Red and agree with this. The actual things that happen that kick off the nuclear reaction are kind of crazy and I can see how it would be very difficult. However, you know it is possible and the shape and structure of it. Any nation state has the resources to do it and it would not take them very long because the physics are all sorted. I actually kind of doubt America could even just produce another nuclear weapon on demand because we have lost a lot of the how-to institutional knowledge.

I think enough is known now to really narrow down the problem to something a nation state can do.