We had Soviet nukes stationed in Czechia too. Does that make us a former nuclear power? I thought not...
Slava Ukraini
What do you think, how many hours does it take to remove and jury-rig launch signal electronics for a motivated nation state at the cutting edge of weapons technology? If the Soviet troops had agreed to leave the bombs in situ, Ukraine would have had some sort of nuclear capability within the week. (And even if the Russians had sabotaged it, Iran and NorK prove that obtaining or refining the fissile material is far harder than explosives lensing and ballistic missile delivery.)
For how long?
Nukes need maintenance. To maintain them, you will need to rebuild the entire supply chain on Ukrainian territory. Do you even have the necessary know-how? What percentage of GDP are you willing to spend on it?
Until today, Ukraine has lower GDP than Czechia. In the 1990s, it was even worse. With their economy destroyed by decades of Soviet rule, they were happy to survive somehow.
Tangentially, it is well possible that Russian nukes are actually under-maintained, for the very same reason: it is expensive to keep them in working order, and Russian economy is not very strong. Perhaps most of them would not explode. But we'd better not find out.
You could just rip the PAL out and build a new detonation timing system, but then you'd be re-doing a large part of the trial-and-error phase of the manhatten project.
It's not something that could happen in hours or weeks. Realistically more like months or years.