Emergency Essentials - https://beprepared.com - has been around a long time and their flat rate shipping can’t be beat. They used to carry Mountain House but have their own brand now. I’ve never bought any long term storage food as it can be expensive. It’s definitely a way to be stocked up quickly with 20-25 year food though. Much of it can be done DIY with buckets, mylar bags, a way to seal them and O2 absorbers or in some cases, desiccant.
There’s also the one that Bongino advertises, Patriot Supply - https://mypatriotsupply.com/
There are some things to consider like container size. Five gallon buckets are heavy, take up vertical space and won’t fit everywhere. Also, once you open one, it’s a lot to go through. A lot of people prefer #10 cans for that reason.
The DIY versions can be regular canned goods from the store, home canned goods. Sugar and salt last forever but will harden. Rice, beans and pasta last a long time with no special storage.
I agree with https://beprepared.com for freeze dried foods.
Very long shelf life!
For pure survival there are calorie dense bars of food designed for life rafts and minimal storage areas (apartments/ bug out bags) that fall under the Safety of Life at Sea (SOLAS) standards. Thousands of calories (and nutrition) per bar. Not flavorful meals but big value for the buck.
https://www.firesupplydepot.com/sos-2400-calorie-emergency-food-bars.html
https://www.lrse.com/products/seven-oceans-emergency-ration
Don’t forget water! Catchment systems if you have rain and life straws for filtering
https://www.walmart.com/ip/LifeStraw-Personal-Water-Filter-for-Hiking-Backpacking-Travel-and-Emergency-Preparedness/150237363