Thats something you can try, but it doesn't have a closed side, which lets too much heat escape and would cause more time to bake for something like a pot pie.
If you want them fresh, for sale at a place like a farmers market, then you may have to set up shop early, and place some pies in the oven probably 30 minutes before people start showing up (or however long it takes to bake one). As you sell a pie, place another in the oven.
Realistically though, if you are selling anything with animal products in it, you will have to bake them hot enough and long enough to kill the bacteria, and I doubt a flash oven would do it in 5 minutes or less.
If you want something like this baked that fast, you are going to lose something in the process:
Pie integrity (chewy, hard, or raw crust and insides), safety (heating long enough to kill bacteria), or quality (have to be made with more crust, less filling, and smaller sizes).
The only other option is frying in a deep fryer, which seems the only way you could get what you want in the amount of time you want it. They heat up hot enough, cook quickly, and can heat the insides of pretty much anything enough to cook it and kill the bacteria.