"A gun type" of nuke is sufficient to achieve most, and usually all, of the goals some small group building a nuke would have.

We are all fortunate that as fc417fc802 mentioned, refining the materials proves to be quite challenging and I see no particular way that AI could possibly make that any easier. If it was as simple as building a gun-type nuke banging together any uranium together to get a big bang we'd be living in a very different world.