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OS-Images and Tool-Chains for Linux can be found at: Linux.-Kernel for Myon & Trizeps or Debian/ Ubuntu OS for Myon & Trizeps
OS-Images for Android you will find at: Android OS for Myon & Trizeps
Informations regarding U-Boot you will find here: Bootloader
For information on how to build images for Windows 10 IOT see Windows 10 IoT. (2019Q3)
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