B4R Question MCU web-server: how to stream a file to a client ?

1. If you can use B4J with a RPi or something similar, then it will be much simpler and work better.
2. Example of a very simple http server: https://www.b4x.com/android/forum/threads/esp8266-wifi-remote-configuration.68596/#content

You should read the file and write it as the request response. Set the response content type to: application/octet-stream