Can't think of many countries besides Canada and US that would not starve in NATO if such a necessity arose, and that's because they produce lots of cereals.
All the other countries in NATO are major food importers.
All apart from France, Netherlands, Spain, Denmark, Poland, Hungary, Lithuania, Turkey, Italy and Ireland.
Interestingly the US is borderline now depending on how you measure food imports and exports.
The average ribeye steak you serve in your barbecue joint can feed a family of 4 in war time.
Italy is not food self-sufficient, it relies heavily on imports of cereals, animal feed, oils, and other.
We add value up the chain (with hams, cheese, etc), but bar fruits and vegetables where we are okay-ish, we cannot feed ourselves. Its been decades that even our own pasta is made out of canadian and us cereals. We simply don't have enough, let alone we don't have good quality cereals.
On top of that, our production is super reliant on imported fertilizers and chemicals. We would borderline starve in case of isolation.
Wars do not start by mutual agreement of all belligerents. If anything, usually the opposite.
Yeah, those pesky Ukrainians waging war for the pleasure of it.
But stop framing it as "defense", we've been almost exclusively the ones attacking, not defending. It's us being the bad guys.