Build me a mobile app -- 2

Hi, Good Day, We have nopCommerce website for our business. Now we need mobile. For that we have nopcommerce API which was developed by seven spikes. We need front end template that should incorporate with API. 1) So We need mobile front end to configure with nopcommerce seven spikes API 2) Flutter / React Native preferable (Angular is optional) 3) Should cross platform supportable 3) Should be create prototype first. Based on that only we awarded the bid 5) We need it in15 man-days. If you don't having experience with nopcommerce, please don't bid. Thanks.