The irony here is that nuclear weapons are actually safer to have lying around than conventional weapons; The amount of work that it takes to actually arm and activate a warhead is higher and you get basically one chance to get it right or it locks you out and self-defeats.
For anyone who is curious, there's a wonderful short video on PALs and how they isolate a nuclear warhead from the outside world: https://www.youtube.com/watch?v=F1LPmAF2eNA
Nukes are also not very stable long-term Their fissile payload is radioactive after all, and as it decays it becomes harder and harder to achieve prompt criticality.
They're more stable in the sense that it takes active effort to move them to the exploded state, while chemical explosives need active efforts to keep them unexploded.
However, that does not stop adversaries with physical access from dismantling the warhead and extracting the enriched fissile material. In a practical sense, easily obtained nuclear weapons are probably more dangerous than TNT UXO, or at least possess the potential to be used for greater harm.
For anyone who is curious, there's a wonderful short video on PALs and how they isolate a nuclear warhead from the outside world: https://www.youtube.com/watch?v=F1LPmAF2eNA