The only illegal characters in a username are ":" (field separator), "\n" (line separator), and "/" (filename separator). Restricting usernames to the legacy posix character allowed set (for filenames, so the $HOME directory is creatable on VFAT and similar) means you can't have UTF-8 usernames. Linux allows any character but / and NUL in filenames. Since root is creating these entries, we assume root knows what it's doing.

syntax: glob
.config*
generated/
kconfig/mconf
kconfig/conf
toybox
toybox_unstripped