I went there as well! Actually I went there during the break and the lines were really huge (although everyone had just a few articles).
Observing this obviously improvable situation during lunch, I came up with a first idea: When it’s time to grab lunch, usually workers are in a rush. They want to eat healthy, quick & cheap that’s why supermarkets are considered as a great alternative compared to restaurants or fast foods. However, stores are really busy during lunch break and people have to queue for so long because of the check-out/payment. What if there was an app on which they could pre-order and pay for their food so that they can pick it up on a locker by the entrance of the store without queuing. Extra products or golden lockers might be offered from time to time in order to maintain customers loyalty. What do you think about it?
Oh, and there is also this article by Figaro on the BonApp!