App for Esp8266 devices

I would like it designed and built. We have developed a product called WiFi switch's and we have used the firmware for it called sonoff tasmota. Following is the link to the firmware [login to view URL] which I have used. I need is an app which works like yeti app which should work in both iOS and Android [login to view URL] You can even refer the code base of the yeti app from https://github.com/arendst/Sonoff-Tasmota/wiki/Yeti---Smart-Home-mobile-app-for-Android-&-iOS And also i am looking a bit advancing the app by providing some more features like adding bulbs with varying the brightness, controlling the fan speed , detecting the device and getting it connected to the wifi network to which the mobile is connected to. Previous esp8266 based projects experience is mandatory Let me know , how much do you charge and how many days it will take to complete the app