Is there a way to have NSH loaded as the init task from an sd card?

[Nimish Telang]

I’m trying to load nsh as the init task from an SD card on the SPRESENSE 
CXD5602 board (a FLAT build). Normally it just calls nsh_main from the user 
init function when INIT_ENTRYPOINT is defined.

I’m not able to determine which combination of symtab options, if any, I should 
use with the init filename option; when I have NSH create it there’s a symbol 
typing clash in the auto-generated symtab_apps.c

symtab_apps.c:282:11: error: conflicting type qualifiers for 'g_nsymbols'
  282 | const int CONFIG_SYSTEM_NSH_SYMTAB_COUNTNAME = 
sizeof(CONFIG_SYSTEM_NSH_SYMTAB_ARRAYNAME) / sizeof(struct symtab_s);
      |           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
symtab_apps.c:37:14: note: previous declaration of 'g_nsymbols' with type 'void 
*'
   37 | extern void *g_nsymbols;

In effect, I’d like to be able to have the board boot up with NSH to do some 
configuration via a script, then have the NSH memory be clear for the 
executable.

Nimish