They want the deterrent. Notice how all the talk about regime change in North Korea stopped once they proved they could build basic fission type weapons.
All you need is fission type weapons and some kind of basic delivery system that can work to threaten something valuable. North Korea is able to threaten Seoul with basic short range missiles topped with little boy style nuclear weapons. And that’s super easy to build once you get past the industrial issues. Then you have a deterrent.
For Iran, they already have basic short and medium range ballistic missiles. Once they’ve got the fission bombs on top of them, they could threaten Ridayah and the Saudi Arabian oil fields. Then the world will stop talking about regime change there.
