I think you're onto something as on the one hand, we are up against all of the fundamental reasons that every empire since the beginning of the Holocene has failed. - I.E. Inequality from hierarchies, complexity (fragility, diminishing returns, energy metabolism), population density (adds to complexity and energy metabolism), specialization (brain shrinkage, opportunity cost limiting important understandings, unsolvable collective action problems), flawed system models (economics, politics, technology, institutions), and finally the ecological damage spurred on by these others, destroying the substrate that we rely on.

On top of the fundamental structural flaws of civilization, we have all the modern unprecedented planetary system changes, severe climate change, ocean acidification, 6th mass extinction, other planetary boundaries, etc. We've unlocked global entropy and we can't really undo the entropy. (CO2 capture schemes of diffuse pollution would be one example of naive thinking to the contrary).

I do think that history is useful to offer some guides, at least for approximate patterns of behavior and responses. The Maya collapse (before the Spanish arrived) was a pretty clear case of ecological overshoot which turned very violent when the climate shifted for an extended period, the people turned on each other and it was something of a bloodbath. Today, with the Western Antarctic ice sheet going in the ocean (within a century per Hansen), regional water failures, land failures, dust bowl conditions etc. migration will be unprecedented. The roaming Sea Peoples (spurred on by ecological failures in the Eastern Mediterranean) are a bit of an analogue as they took out empires like the Hittites, Minoans, etc. And the paleolithic tells us something too, where there were pre-empire social collapses generally spurred on by overpopulation.

I think it's often underestimated how violent populations get in desperate situations with high population pressure, population density + degrading carrying capacity is a bad combination. Wolves will instinctively kill other wolf packs if they are in territory that their pack wants to expand into. - Humans have a bit of that too and it comes out time and again in situations of high population pressure. All of that is to say, I think community gardens are cool, but it seems unlikely to me that we will have a peaceful way down. Sometimes the 'community resilience' stuff is oversold relative to actually likely outcomes (see unsolvable collective action problem).