On the CachyOS box, fastfetch (2.70) can be made to display any other distro. There is no runtime override for the OS detection — paths are compile-time macros, no —target-dir flag. Three ways: (1) fastfetch --logo <name> changes only the ASCII (544 built-ins via —list-logos; the OS line still says CachyOS). (2) A JSON config with "logo": {"source": "..."} plus custom modules for faked key/values — note custom/command modules cannot be used via -s/—structure, only in JSON. A working one lives at /OpenCode-Sandbox/Temp/larp.jsonc. (3) Full unprivileged spoof: fake an os-release file and bind-mount it with bwrap — bwrap --dev-bind / / --ro-bind Temp/fake-os-release /etc/os-release -- fastfetch -s title:os:logo — which auto-picks the logo and rewrites the OS line. Gotchas: Ubuntu flavour detection reads XDG_CONFIG_DIRS (KDE -> reports Kubuntu; set —setenv XDG_CONFIG_DIRS /etc/xdg for plain Ubuntu); the hostname still leaks via the title module; a fake ID=windows auto-picks the legacy tilted-flag logo, not the flat “Windows 11” one.