Ukraine didn't give up nukes for false guarantees - it gave them up to not become sanctioned to the level of North Korea and Iran (while at the same time it didn't even have the launchcodes because nobody wants to get Dr.Strangelove-d)
And considering the level of poverty there in the following decade, chances are nukes would've just gotten sold off, just like its carrier
There's no clear evidence that sanctions were a strong motivator for them. Ukraine gave up their nuclear arsenal in exchange for security assurances and economic support. At the time non-proliferation was an international movement which Ukraine aligned with, it just made sense. In hindsight though, what Russia did isn't surprising, but the US seemingly abandoning them to indirectly support Russia is surprising.
And considering the level of poverty there in the following decade, chances are nukes would've just gotten sold off, just like its carrier