I'm off grid, but not nearly as self-sufficient as say, old order Amish.
Homesteaders had 20 acre lots, at least. This could feed about 10 people, using a similar setup as you show. An orchard would provide the most food per acre, while ranching provides the least. Although ranching or shepherding is a good option in dry or infertile land where farming may not be an option.
To have a decent quality of life, it really takes a community, at least a village. You can theoretically survive on as little as 2 acres, but your life will be miserable if all trade is cut off. Imagine getting all your food, clothing, materials, everything, only from your own property. I have over 5 acres and it would provide a lot more food and materials that I need, if it was properly developed. But it also will not provide an enormous amount of things I may need. That's why natives travel so much. Tribal peoples can migrate many miles every year, to get the resources they need. Being landlocked is sort of like being marooned on a tiny island, but without the sea.
Another thing is heat in winter. For a tiny home, 5 acres of hardwood forest is needed to supply firewood sustainably. Less than that and you will run out.
So, ideally, the more land you have, the better. But owning it may not mean anything, post-apocalypse. Having 1 acre next to a national forest is probably better than 20 acres in a suburb of a mega metropolis.
Hopefully you will have a peaceful community and a trade network post-apocalypse.
In a post-apocalyptic scenario peaceful people will basically be hunter-gatherers and ruin explorers. I expect small farms will almost immediately be raided for food, repeatedly. Starving people are going to do whatever to survive, especially with no cops around. You could try hiding your food, I guess.
You could either build a bomb shelter and fortify it like a castle, hoping your defense will hold against frequent gangs, or, hide in the wild hoping no one will find you.
Another option that rich people do is the secret house. You basically look like you're dirt poor. So thieves leave you alone. But under your pathetic-looking abode is a secret mini-mansion. Think of an ugly tin shack with a luxurious basement accessed by a secret door.