I bought an Instant Pot stick a few months back. Tougher cuts of steak and pork chops were disappointing. Haven't tried fish though I live next to the ocean. What works particularly well are duck legs and chicken thighs (check your temperature). I think beef short cut ribs (a.k.a. kalbi) will work well but I was SVing mine in marinade. Big mistake.

For efficiency, I got a small cooler chest from a Big Brothers Big Sisters yard sale and made a lid out of some insulating foam (didn't want to put a hole in the original lid). Heat loss is minimal.