Wild strawberries grow small and give very tasty little fruits. They are easy to grow on a balcony though quite dramatic and need plenty of water when there is sun and heat. First year they didn't give almost any fruit but second year on I have a handful of harvest daily all of late summer. Very satisfying.

I've tried having small bushes of goose berries but they got hit with mildew, probably because there wasn't enough exchange of air.

Try different things, see what works where you are.