I'm an embedded engineer who's currently working for a large company based in US and have been involved in multiple product development (more than 10) in which BLE capability is always included. I myself was responsible for developing firmware for 4 different projects including activity trackers and smart home products. Besides, as I started working for this company when it was still a startup (with limited workforce), I also involved in other non-embedded tasks including iOS/Android app prototyping and SDK developing for incorporating with BLE chips. Especially for iOS, I was singlehandedly cloning the infamous LightBlue app (https://itunes.apple.com/us/app/lightblue-explorer-bluetooth/id557428110?mt=8) and implement some add-in features to make it compatible with our devices. This app is later used by all of our engineers for feature developing and debugging.