What is the purpose of CONFIG_TARGET_INIT_CMD ?

What is the purpose of this configuration and where will it be used?

root@d33cdc59f198:/home/openwrt# grep "CONFIG_TARGET_INIT_CMD" .config
 --- Init configuration options                                         
 (/usr/sbin:/usr/bin:/sbin:/bin) PATH for regular boot                  
 ()    Environment variables to set when starting init (start with none)
 (/sbin/init) Init command ------->>>>>>>                                               
 [*]   Suppress stderr messages of init                                 

What is the difference between configured and unconfigured? I'm using initramfs, when I configure it to /init, it fails to boot. When it is necessary to customize the configuration of this option?

it's a binary, or a script, not a dir.

as it says in the link, it kicks off all the other daemons and processes, if you remove it, nothing will work
you shouldn't customize it, unless you have a fitting replacement in place.