A no first use policy is never going to happen, because it completely flies against all of the prevailing wisdom about nuclear deterrence[1]. Nuclear powers benefit heavily from ambiguity about where their "red line" is that would need to be crossed for them to use nukes, because that limits the ability of others to act against them for fear of crossing the line. Drawing a lower bound on where your red line is, like with a no first use policy, frees up others to act against you because they know how far they can safely go (literally anything short of using your own nukes in the case of a no first use policy).
[1] https://acoup.blog/2022/03/11/collections-nuclear-deterrence...