I use to shop at Lidl. As you say, they carry a limited SKU assortment. But I have found it doesn't really matter. When I go to a grocery store that carries more variety, it feels exciting, but in the end it makes no difference. As long as I can get the essentials, I will manage. I don't need 20 types of hamburger dressing. I can make my own from first principles. I don't need 40 types of yoghurt. I buy can natural and eat with fresh fruit. And so on.

Lidl also has this interesting approach that they rotate some assortment. You can't find everything all the time. But once you realize that certain things periodically come back, you pick them up when they are in stock to make sure you have them at home. It is not as convenient, but if you make it a habit, it is a very minor disadvantage.