KMX files
Used by: : Keyman Desktop, Keyman for macOS, and Keyman for Linux.
Description: : A .KMX file is a compiled keyboard file.
Details: : A .KMX file is compiled in Keyman Developer from the Keyman source file (.KMN) and icon for the keyboard (.ICO/.BMP). Note that .KMX files are not used for Keyman for Android and Keyman for iPhone and iPad.
Distributed with keyboard: : This is the keyboard file. It must be distributed with your package to allow people to type using the keyboard you have developed.
Reference:
