According to present-day Ukraine, was it a mistake?
What do Ukrainian political leaders and scholars/intellectuals say about this?
What do Ukraine's general population say about this?
According to some political leaders and a part of general population in Ukraine, giving up nuclear weapons in the past was a mistake. There have been recent calls to reacquire nuclear weapons by Ukraine.
“We gave away the capability for nothing,” said Andriy Zahorodniuk, a former defense minister of Ukraine. Referring to the security assurances Ukraine won in exchange for its nuclear arms, he added: “Now, every time somebody offers us to sign a strip of paper, the response is, ‘Thank you very much. We already had one of those some time ago.’”
Western analysts say the current Ukrainian mood tends to romanticize the atomic past. “The gist is, ‘We had the weapons, gave them up and now look what’s happening,’” said Mariana Budjeryn, a Ukraine specialist at Harvard University. “On a policy level, I see no movement toward any kind of reconsideration. But on a popular level, that’s the narrative.”
In Ukraine, the Crimean invasion and the lengthy war led to a series of calls for atomic rearmament, according to Dr. Budjeryn, author of “Inheriting the Bomb,” a forthcoming book from Johns Hopkins University Press.
In March 2014, Volodymyr Ohryzko, a former foreign minister, argued that Ukraine now had the moral and legal right to reestablish its nuclear status. In July, an ultranationalist parliamentary bloc introduced a bill for arsenal reacquisition. Later that year, a poll showed that public approval stood at nearly 50 percent for nuclear rearmament.
Last year, Ukraine’s ambassador to Germany, Andriy Melnyk, said Kyiv might look to nuclear arms if it cannot become a member of NATO. “How else can we guarantee our defense?” Mr. Melnyk asked.
Ukraine Gave Up a Giant Nuclear Arsenal 30 Years Ago. Today There Are Regrets. By William J. Broad. New York Times, February 5, 2022: https://www.nytimes.com/2022/02/05/science/ukraine-nuclear-weapons.html
Pavlo Rizanenko, a member of the Ukrainian parliament told USA Today that Ukraine may have to arm themselves with their own nuclear weapons if the United States and other world leaders do not hold up their end of the agreement. He said "We gave up nuclear weapons because of this agreement. Now, there's a strong sentiment in Ukraine that we made a big mistake." He also said that, "In the future, no matter how the situation is resolved in Crimea, we need a much stronger Ukraine. If you have nuclear weapons, people don't invade you." On December 13, 2014 Ukrainian President Petro Poroshenko stated that he did not want Ukraine to become a nuclear power again.
On April 15, 2021, Andriy Yaroslavovych Melnyk, Ukrainian ambassador to Germany, told Deutschlandfunk radio that if Ukraine was not allowed to become a NATO member, his country might have to reconsider its status as a non-nuclear weapon state to guarantee its defense.
In February 2022 (in the wake of the Russian invasion of Ukraine), Ukrainian president Volodymyr Zelensky renewed such sentiments, suggesting that Ukraine would potentially view the Budapest Memorandum as invalid should its security guarantees not be met.
As of 2022 only three Ukrainian parties support bringing back nuclear weapons: Svoboda, Radical Party of Oleh Liashko, and The National Corps.
Ukraine and weapons of mass destruction: Wikipedia: https://en.wikipedia.org/wiki/Ukraine_and_weapons_of_mass_destruction
At least according to the first president of Ukraine, it was not a mistake. In this interview he said that Ukraine with nuclear weapons would be like a monkey with a grenade. Also according to another interview by Kravchuk, it was the West, who wanted to make Ukraine free of nuclear weapons.
There is also a video of that interview by Kravchuk, but without any translation, so not sure if it can be useful as a reference.
However for those who interested here the original video of the interview to ukrainian TV.
Ukraine could not launch these weapons with the push of the button; Russia had all launch codes. Still, at least raw materials were probably reusable, no need to spin lots of centrifuges to purify uranium. These weapons could have been rebuilt instead. The country does not need to be rich to possess them. Pakistan does.
I think Ukraine has done the right thing by dismissing the nuclear weapons and making the world more secure. This earned the notable support for them from the world and probably contributed that it is very difficult to persuade most of the world that Russia is fighting a defensive war against Nazi. Nazi just do not destroy they nuclear weapons. Would be highly unusual for them.
Not many countries get that much support of all kinds from the world, not many refugees are so welcome in the world, not often folks raise millions of donations in days to buy a Bayraktar for another country. Least not the last, some Russians tell the truth and then go into jail for seven years, also respect. I would not trade that for a bunch of nuclear rockets that I probably could not use anyway because the enemy may strike back with the similar ones.
Ukraine never actually have nuclear arsenal. It was like US nukes on German military bases. Geographically, it are in Germany, but it is the US nukes. The same way Soviet, and then Russian nukes were on the Ukrainian territory. According to wiki, it was under the Commonwealth of Independent States control.
So, the question itself is about something hypothetical, sort of "What if?".