etc1tool 29.0.6-28 (armhf binary) in ubuntu mantic

 etc1tool is a command line utility that lets you encode PNG images to
 the ETC1 compression standard and decode ETC1 compressed images back
 to PNG. It is part of the Android SDK for working with media files
 for game apps. The standard for the ETC1 texture format is here:
 http://www.khronos.org/registry/gles/extensions/OES/OES_compressed_ETC1_RGB8_texture.txt