Maybe you can print lists of commonly purchased fruits, vegetables , meat and cereal with checkboxes?
To be honest, I usually buy 4-6 types of vegetables, a few types of fruits, chicken, pork, fish every week so it’s always within my budget but I cook them on different days using different recipes/cooking methods or sauces for each type of ingredients. I might buy something fancy once in a while like fresh salmon $6-12 but I’ll adjust my budget by buying another cheaper type of meat or vegetable.
As long as my family sees a different type of vegetable or if the dish looks different every day, they’re ok. Eg Monday – broccoli, Tuesday – spinach. We also eat pork a few times a week, but I cook pork cutlets with tomato sauce and onions, steamed pork, stir fry veggies with pork slices. Generally I just have a menu of things I can cook whether I’m tired or not so it doesn’t take too much effort. Or I would marinate different batches of meat and just cook them on any day.
For picky eaters, I may chop some things finely like vegetables and hide it in an omelette with other things like minced meat or use some ingredients to mask the flavour eg in a stew.