I'd class UPF as foods that have ingredients like gums, emulsifiers, gelling or foaming additives, preservatives that make products palatable or long lasting - ingredients I wouldn't have in my cupboard.
I do buy hummus though - Cooked Chickpeas (50%) (Chickpeas, Water), Water, Rapeseed Oil, Sesame Seed Paste (13%), Concentrated Lemon Juice (4%), Garlic Purée, Salt, Preservative (Potassium Sorbate).
The preservative is the only thing that I wouldn't have in my cupboard.
Flatbreads - I try to avoid the ones with a million ingredients - Wheat Flour (Wheat Flour, Calcium Carbonate, Niacin, Iron, Thiamin), Water, Rapeseed Oil, Wheat Gluten, Wheat Fibre, Spirit Vinegar, Yeast, Emulsifier (Mono and Diglycerides of Fatty Acids), Preservatives (Potassium Sorbate, Calcium Propionate), Raising Agents (Disodium Diphosphate, Sodium Hydrogen Carbonate, Calcium Phosphate), Salt, Stabiliser (Carboxymethyl Cellulose), Acidity Regulator (Citric Acid), Wheat Starch, Wheat Flour
and go for the Crosta and Mollica ones (expensive though!) or just normal pitta bread which is generally flour, water, yeast and oil and very cheap.
Mayo, soy sauce, teriyaki etc I'm sure are UPF but I still buy them.