Hello Hiroyuki,
I understand your request and unfortunately currently there isn't a sample on https://github.com/Azure/azure-sphere-samples to setup a local http server on Azure Sphere for configuration
purposes. As you mentioned the Sample: Wi-Fi setup and device control via BLE - reference solution demonstrates how you might complete
Wi-Fi setup and device control of an Azure Sphere-based device through Bluetooth Low Energy (BLE) using a companion app on a mobile device
and without connecting to the Internet Servers.
You are correct as well, on Azure Sphere High Level apps you need to leverage C/C++ code.
The
azsphere command-line utility will allow you to configure the device without connecting to the internet, though you need to connect your device to the PC over USB.
If you develop a High Level app to act as a simple Web Server for configuration purposes you should start by looking at the Sample:
Private Network Services - it will guide you on how to implement a basic TCP server. From there you can leverage Azure Sphere Application Libraries.
Finally I would strongly suggest that you add a new feature request on
Azure Sphere Feedback Forum so others can vote and we prioritize it (share the link if you do so).
In case the information in this post is helpful , please feel free to mark this response as answer so that it can help others searching for similar questions.
Thank you so much!