The Budapest Memorandum is meaningless and your tone is that of an asshole.
The other countries didn’t have the power to create nukes nor launch the ones in their countries. Thus not nuclear powers.
Whenever I have workmen doing major renovations on my property I tend to have to sign something when the job's complete. It's not unusual at all for that wrap-up to involve some confirmation (sometimes even me signing a bit of paper) to the effect of, everything left behind once they depart is waste for me to dispose of
Every now and again, I'll get a call a few days later from a contractor to the effect of, "I think I left some of my tools in your garage". Thing is, whatever you think morally about it, if he had me sign a bit of paper saying that I get the job of disposing of everything he left behind, he's made his "tools" my my "waste" to get rid of. So it's my property. He can't just walk into my garage and take those tools back; he has to ask me if I'll be so kind as to hand them back. Because I'm a nice guy I will give him his tools back, but the letter of the law says he and I both signed paperwork to the effect of, whatever he leaves behind is mine therefore it is my decision not his.
So if he had done a particularly poor job, I could refuse to return them unless he redid the unsatisfactory work. All kinds of scenarios play out but the main thing is, it's up to me if he gets his tools back, because legally they're not his and it's not up to him. The only real complication I'd have is if the tools were on a hire purchase contract.
That's what happened with the nukes in the independent states.
This article by no means is on Ukraine's side, but it goes pretty thoroughly through the reasons why some in America wanted Ukraine to hang onto the nukes and become an independent superpower, while others lobbied Ukraine to hand them over to Russia.
https://nucleardiner.wordpress.com/2022/02/06/could-ukraine-have-retained-soviet-nuclear-weapons/
The article confirms Ukraine didn't have the means to use the nukes but it did have technical ownership of them. It could've done what Khazakstan and Belarus did, but instead it decided to return the nukes SIMPLY IN RETURN FOR RUSSIA SIGNING A NON-AGGRESSION TREATY WITNESSED BY USA AND UK. That decision didn't just benefit Russia as well as Ukraine, it put the "brotherly love" between the former SSRs into writing. And that choice is the only thing that kept Putin's foot on the brake pedal for so long... Without the Budapest Memorandum Ukraine would've been Groznyfied as soon as Putin thought they were ready to be absorbed into his fascist empire. What changed? COVID, and America booking it out of Kabul. If there ever was a time to commit a treaty violation that'd drag the USA and UK into a regional dispute, it was after Biden ballsed up Afghanistan.