A ketogenic diet plan is not a "special diet" that requires special foods. There is no need to buy any "low carb" packaged foods. Ketogenic foods are essentially just real, whole foods which are close to their natural state. In other words, they are not highly processed. The only exception to this is the category of artificial sweeteners. These are highly processed. However, I think these are important to include in a low carb diet plan, because a small amount of fake sweetener has less of a negative effect on health than the standard amounts of sugar in sweetened foods. Some people may prefer more natural sugar alcohol sweeteners, but studies have shown these are "antiketogenic" and can derail the process of ketosis for some. They effect each person differently, so you'll have to test to see if they effect your health or weight loss goals.
Our bodies are incredibly adaptive to what you put into it – when you overload it with fats and take away carbohydrates, it will begin to burn ketones as the primary energy source. Optimal ketone levels offer many health, weight loss, physical and mental performance benefits.1There are scientifically-backed studies that show the advantage of a low-carb, ketogenic diet over a low-fat diet. One meta-analysis of low-carbohydrate diets showed a large advantage in weight loss. The New England Journal of Medicine study resulted in almost double the weight loss in a long-term study on ketone inducing diets.