MA
Your question doesnt really make sense
A fruit, is by definition food. An Esrog isnt really edible, it certainly isnt eaten (if you need to soak in in sugar that deosnt count, a car tire would be edible if soaked in sugar) Thus it isnt a fruit.
Supermarkets dotn sell tose berries you see growing on bushes in abandoned lots, becasue they arent edible.
Of course a fruit is also the part of a plant that contains seeds, but there are many such fruit that arent sold