When Microwaves first came out they were huge but with a tiny cooking area and they were not affordable, and were mostly in business kitchens and a few restaurants. I would love a freeze dryer but the cheapest I have seen is $1600 and they only have 4 small trays.
Ultimate? No. But it’s part of a suite of food preservation tools. Without watching the video–YouTube is doing that annoying thing where it requires sign-in–I can say that you need to be able to use multiple food preservation techniques. You should learn to do canning as well, and you really need an effective vacuum sealer (that can use heavy-duty mylar, versus specialty plastic bags) in order to effectively preserve freeze dried foods, and those mylar packages need to also be sealed in containers away from pests that might chew through the bags.
Freezing food, by itself, is only useful as long as you have electricity. If you’re entirely off-grid, and have over-capacity solar system, that might be good enough, if you have a LOT of freezer space. The least expensive freezers I can find are around $25 ft^3; costs decrease slightly when you’re talking about large walk-in freezers, but that requires a building that can accept a walk-in installation, and $25,000 for a 1000ft^3 freezer is more than most people can afford.
Drying foods in general is decent, and high sugar content–fruits in particular–can lasts decades if they’re vacuum packed with oxygen absorbers. Even though dried foods will have some moisture content, the sugars act as a preservative and prevent the growth of bacteria. (Sugar curing meat is definite a real thing, much like salt curing; more on this in a sec.)
Canning is good for some things, but certain things can not be safely canned, and canning is slooooooooooow. It also requires a botttle/ring/seal for each and every thing that you can; seals are not reusable.
Dry goods don’t need to be freeze-dried; you can vacuum seal most of them with oxygen absorbers and desiccants, and be fine. Things like flour can mostly be put in large buckets with gamma seal lids and be okay for years at a time. White rice stores wonderfully for the long term, as do dried beans. (However!, dried beans must be soaked prior to cooking, the soaking water discarded prior to cooking, and can not safely be eaten raw. Cooked canned beans are a better choice for anything other than very long term storage.) Brown rice has a high fat content relative to white rice, and has a bad tendency to spoil, as do nuts of all varieties; I haven’t tried vacuum sealing them with oxygen absorbers and desiccants to see if that preserves them for longer than a few years.
Meats can be preserved by curing. This is, however, a very exacting process, and it not recommended unless you know what you’re doing. It requires a temperature and moisture controlled container and a few weeks of time, and fucking it up means that you kill yourself with bacterial contamination.
Freeze drying works for complete meals where you can’t freeze things, and you want food that’s going to be ready-to-go, either rehydrated or dry. Yes, you can eat freeze dried things without reconstituting them, although it’s not terribly pleasant in some/many cases. If you, for instance, made a stock-pot full of red beans and rice, freeze drying would be the ideal way of preserving it and making it shelf-stable.