Pakistan effectively doesn't have nukes. Pakistan's nukes are kept in a de-mated state and it takes hours if not days to get them ready for launch. They're too close to terrorist groups in the Middle East (geographically and otherwise) to have nukes that are a button-press away.

This gives them enough deterrence against a total invasion (because of the "what if" factor) but not against random airstrikes.

It doesn't guarantee of course, but one does not face external existential threats.

India will not dare to overrun Pakistan nor does it want to. (Few crackpots from both those countries aside)