>Vast majority of things must be flown or shipped in. I am hard pressed to see some "techno libertarians" doing techno without Amazon/Temu/Walmart/<insert fav vendor> in 24h drop ship.

I think this is an unreasonable bar. All the fertile land in the world has been accounted for. There's no way to accomplish that type of sustainability without conquering existing land or some major technological breakthrough.

I think a fair bar would be economic sustainability. Plenty of countries depend on trade for food, but can make up for it in exports.