Livestock raised on grain will return only 10-20% of the calories in that grain as meat. If food self sufficiency is a goal, livestock that can forage like goats and chickens are best. I might mention bees as forage animals as well.
Humans can forage too. Learning what is edible in your natural environment is good for humans as well. Besides edible forage plants… fishing especially can be a great source of protein that doesn’t “cost” anything but time and some very simple gear. Hunting game can work but I think fishing is more practical if the environment suits. Hunting is more seasonal, likely to be regulated (assuming we aren’t SHTF) and requires a lot more skill and expensive gear compared to fishing.
Of course eating more grain and vegetable calories directly (vegetarian) is also helpful. Chickpeas are very versatile non meat protein source as are beans in general. Dry beans store easily and while most need to be soaked before cooking, it’s not much of a hardship if the alternative is being hungry.
Another useful point is to avoid food waste and spoilage. Freezing, canning, dry storage, cool storage… whatever works but make sure it works. Spoiled food is still fine for animals of course but again - you are only getting back 10-20% of the calories. And of course… finish what’s on your plate!
Black soldier flies / larva are an interesting protein source for chickens or other animals perhaps. The larva will consume all kinds of leafy waste. There are plans online for larva “farms” that are easy enough. “BSL” is a common abbreviation to search on. Chickens + BSL is an interesting system if larger animals are impractical.
Mushrooms grow easily enough on wood shavings and can be grown almost anywhere because they don’t need light. Mushrooms are a good way to liven up a (mostly) vegetarian diet and add some protein that might otherwise be tough to get.
Hydroponics can be a little “fiddly” but if water and/or good soil is scarce it can make sense. There is a guy in Australia with a neat hydroponic setup using roof gutter and rock wool for growing media. His youtube channel is worth a look if you are interesting in hydroponics on the cheap. Ollas (terracotta jugs that seep water) in the soil can be an easy way to save water if that’s what is scarce. Drip irrigation may be easier still with all the cheap plastic tubing available though it will be less sparing with water use.
If fertile soil is an issue “Terra Preta” and chinampas are interesting rabbit holes. Otherwise yea… composting and getting your NPKs where they need to be is key. Humans and livestock produce all three if need be. Having plants access them safely and hygienically is the tricky bit but with enough time those resources can be safely cycled through growing fields.
Permaculture is interesting but the community seems to thrill at making it complex to understand with systems, classes and what not which puts me off. As best I can tell the revolves around logically sited swales to hold onto water that might otherwise run off and a focus on perennial plants that work well together in the given environment. Can I skip class now?
Food forests are an interesting concept for sure. But basically that’s just planting perennials that produce food: nuts and fruit mostly. That makes tons of sense to me? Trees/bushes and their deeper root systems are better at dealing with scarce water (generally). And you don’t need to plant every year. What’s not to like?