Austria? Brazil? Indonesia? None of those are nuclear-armed states...which means that their "power" is effectively ZERO. It also costs them nothing to slap a signature on a document that has no material impact on their national security, because they have no capability to lose. You seem to have a very....idealistic view of international relations. Let me explain how nuclear disarmament would play out in the real world:
UN Signatories: We don't think anyone should have nuclear weapons.
US/Russia/China/etc: Nah, keeping these "just in case" is an important part of our international influence.
UN Signatories: I guess we will have to forcibly disarm you?
Nuke States: You can try. Invade me, and I'll burn your entire population to cinders, and make your lands glow in the dark for the next 10,000 years. ( https://geopolitics.news/euroasia/russia-adopts-nuclear-firs... )
UN Signatories: Ok on second thought we'll just send you another sternly-worded letter....
And that's how the conversation ends. Because sovereign states that are unable to enforce their will on others have no real power.
>>>What I’m pitching here is for you to contact your national government and encourage them to sign it if they haven’t done so already.
I'm a citizen of not only a nuclear-armed state, but arguably the world's most influential global hegemon: the USA. If any of my politicians even HINTED at supporting such a disarmament, I'd vote them out of office ASAP.
I read the entire treaty here: ( https://en.wikisource.org/wiki/Treaty_on_the_Prohibition_of_... ). The Preamble reads like it was drafted by a drum circle of hippies, stoned on a beach in California. It's not written in a manner that is in any way persuasive to the people who actually need to be convinced: the national security leadership.
If this is a policy you seriously want to advance, I recommend taking a hard look at how national security professionals establish values and objectives, assess problems, and work through cost-benefit analyses in pursuit of said objectives. Know your audience, or you will never talk them into an alternative course of action.