How to imitate the oven on the stovetop?

There is no great solution for an oven on the stovetop, even stovetop ovens aren't that great. The two are entirely different styles of cooking. The only thing I can think of that comes close is a dutch oven as the thick sides conduct more heat around the vessel, but that still gets most heat on the bottom.

If you want to do a lot of browning of the tops of things in a commercial situation then you could invest in a dedicated top grill unit, these are just for that purpose, a bit like a broiler except it's a table-top unit. If you want to brown the top of things and melt cheese every once and awhile but can't have an oven then I would introduce you to my good friend the piezo ignition gas torch which you can pick up in most hardware stores.

Other than the equipment side I'd suggest you modify your choice of dishes and ingredients to fit the equipment you have available. You can struggle trying to re-create oven cooking on a stovetop with mediocre results, or you can learn to make falling off the bone stovetop slow-cooked meats. One approach is more rewarding than the other.

I just remembered form my camping days that I once had an aluminum folding box like thing that would sit atop a Coleman stove. I baked a pie in it and it worked great. You should be able to find one of these in an outdoors store that sells camping supplies.

I made a pizza once on the stove top. I placed a rimmed cookie sheet on top of a saute pan. I put the pizza on the cookie sheet and placed another larger rimmed cookie sheet on top and perpendicular to the lower sheet holding the pizza. This allowed moisture to escape and the pizza came out very good.

It is going to be impossible to get a good immitation of an oven, on the stovetop, due to the fact that there is no way to get a dry heat source on all sides. Baking is a dry-heat cooking method in which the heat comes from all around. The problem you'll have on the stove is that the heat comes from only the bottom.

However if you have a deep enough pan/pot you can "elevate" the protein on a wire rack or even a bed of vegetables, such as onions and carrots, to prevent the bottom from burning. Cover with a tight fitting lid and you will have something that is similar to an oven, but you still won't get much browning like you would in a real oven. So it would be best to carmalize your meat on a higher heat on the stove first then transfer to this type of set up.