Canning fresh meat in an oil bath?
You are correct that simply boiling meat for three hours is not sufficient to make it shelf stable. Commercially produced, low-acid, canned foods must be processed to 240F just like home canned food. The process involves processing the cans in a steam pressure cooker similar to what is done at home at a smaller scale. 1

I have boiled sealed cans with but it is discouraged and I would not trust heating cans to 240F without matching the pressure outside the cans. Any can failure would be spectacular as the water instantly vaporizes and blows an easily-ignitable geyser of steam and oil into the air!

Pressure canners can be a bit expensive but can often be found used. You may need to replace rubber gaskets or safety valves but these are not expensive. 

You may have more success canning using bottles as the bottles, lids, rings, and other equipment is easy to find for home buyers.

Another consideration is that canning recipes are written for specific pressures and cooking times to preserve food quality and give a very strong confidence of food safety. Even if you are confident your cans will hold, you would have to carefully control the temperature of your oil. Home sous vide controllers aren't designed for such high temperatures which means you would have to purchase a more expensive temperature controller or build your own.