libsixel-dev 1.8.2-2.1 (armhf binary) in ubuntu focal

 SIXEL is one of image formats for printer and terminal imaging
 introduced by Digital Equipment Corp. (DEC). Its data scheme is
 represented as a terminal-friendly escape sequence.
 So if you want to view a SIXEL image file, all you have to do
 is "cat" it to your terminal.
 .
 The package is for development.