I've been wondering what tech levels would be SELF SUSTAINABLE. Like the amish lifestyle is a circular economy, everything they need they can make themselves, grow themselves, and compost themselves. Like mostly.
But can you have something like electric motors or wind power in the same way? Can you have electronics? Can you have eReader? Like if you had a town the size of 50.000 people.
Theoretically advances in technology could allow for things like biological computing. Like a variety of seeds to produce plants making all sorts of medicine, or single cell cultures then organize into simple electronics. Not sure how sci-fi that is. But in a way that would be a "safe point" for civilization.
Because even after a limited nuclear exchange which is is getting more and more likely each year we're not going to have any global supply chain left.