Whether you have the required space or not, two other variables complicate any attempt to do this: 1) length of the growing season - Where I live, we have 5-6 months of active growth. Never more than 6. Snow covers the garden the rest of the year. 2) time - Tending your growing food source is one investment in time, but because the food does come in all year at a regular rate, you are forced to spend time prepping it in a way that it will remain edible until the next harvest after the snow melts. It’s a lot of time. We only have about 100 m2 for vegetables but we spend hours a week pickling, canning, freezing, dehydrating, cooking and freezing. If our yields were larger to the point of complete sustainability, it would be a full time job.