Food can be bought either from the shop (not peeptube shop), they appear randomly, so one day you can see an ingredient and I'm the other not
Or during the runs if you happen to find a vending machine
As for shoes, try running at night in the city
If she wants "food" from you, that means simply go to the kitchen with her and cook something without failing it, but first you'll need to buy some ingredients for the recipe, aim for the ramen as it's easier between the two.
Feel free to join our discord and check pinned comments in #rec-discussion, you'll find there video tutorial of cooking both recipies