There are a lot of different things that can be used as a keto taco shell. I prefer to make my own version of a taco shell and make one out of cheese. If you prefer, you can also use low-carb tortillas or even egg wraps that can be found in the grocery store. The main thing to consider is what your daily macros are and how low you want your carb intake to be each day. Some even use lettuce leaves to stuff with chicken and toppings for a super low-carb shell.