In contrast, rewind to the early 1800s and there is zero hope of a ban on the R&D of small arms being effective in the long run. The only thing it might maybe ensure is that no legitimate actors that fall under your jurisdiction are involved in it.
Basically I think that current trends point to an eventual situation where world changing research doesn't require anything more than consumer level compute. Pandora's box has already been opened.
> We don't have pocket nukes
Bit of a tangent but we do, actually. At least depending on if you consider an artillery shell to be pocket sized. https://en.wikipedia.org/wiki/Nuclear_artillery
This one is a bit long to fit in a pocket but you could certainly sling it over your back. https://en.wikipedia.org/wiki/W45_(nuclear_warhead)