Why do you compress the executable? I mean this is a fun part for size limit competitions and malicious activities (upx often gets flagged as suspicious by a lot of anti virus, or at least it used to), but otherwise I do not see any advantage other than added complexity.

Also interesting that "ultra lightweight" here means no error reporting, barely checking, hardcoding, and magic values. At least using tty color escape codes, but checking if the terminalm supports them probably would have added too much complexity......