[rixed]

According to what I've read and watched on YouTube (such as the interesting, if inevitably biased series "Russian Roulette" by ViceNews that I recommend you watch with your brain on and Wikipedia ready to look up every mentioned character), the Ukrainian army had such difficulties with basic supplies that I can't imagine them developing actionable weaponry at all, conventional or nuclear.

Even if some scientists could technically build a bomb, the hard part with nuclear arsenal is not the bomb itself but the launching device.