NuttX has support to USB Mouse and keyboard, whoever only few USB Keyboards will work. I know a keyboard that some users reported to work correctly is the Perixx PERIBOARD-409U Wired USB Mini Keyboard.

I decided to test a generic mini keyboard from China, but it is not working. Most of the time the /dev/kbda is not created and when it is created it is not working:

ABCDF

nsh> ls /dev
/dev:
console
kbda
null
ttyS0
nsh> ?
help usage: help [-v] []

NuttShell (NSH) NuttX-10.0.1
nsh> OTGFS ERROR: ctrl_senddata() failed with: 11

. cat dd false ls ps sleep uname
[ cd df free mkdir pwd source umount
? cp echo help mkrd rm test unset
basename cmp exec hexdump mount rmdir time usleep
break dirname exit kill mv set true xd

Builtin Apps:
sh nsh hidkbd
nsh> hidkbd
Opening device /dev/kbda
Device /dev/kbda opened

If you get some other keyboard working, please comment here!