Issues using nixos-option

There two things I noticed recently on my machine.

  1. nixos-option doesn’t appear to have a man page
$ nixos-option --help
No manual entry for nixos-option
(1) $ 
  1. nixos-option doesn’t support the --xml flag
$ nixos-option --xml
terminate called after throwing an instance of 'nix::UsageError'
  what():  unrecognised flag '--xml'
Aborted (core dumped)
(1) $ 

This is my version:

$ nixos-version
20.09.2610.3d8fa5f7215 (Nightingale)

I was messing with Vue and micronaut on a nixos-ui and noticed this. I found the --xml flag from a different webpage so maybe this is a new feature not in 20.09. Is there any other way to get these options?