That is exactly what it is. And it can be accelerated by slicing thin on racks. Putting in a small fan to circulate the air around. And putting a new bag of cat litter in the bottom with holes punched in it to absorb the moisture. We use a huge stand up freezer so that we can do a whole bunch at a time then vacuum pack it. Only takes about 2-3 weeks and much cheaper than buying freeze dried products, they are crazy out of sight with those prices.
How does the flavor hold up? Freezer-burned meat is pretty nasty.
I dry a fair bit of food with a hot-air dehydrator. Would freeze drying be effective to remove more water from already dehydrated food? I don’t have an extra freezer to devote to freeze drying, though.