[Toybox] Using toybox for poking around weird namespaces?

[Andy Lutomirski]

Toybox's magical ability to present a usable shell without needing to
exec anything is almost perfect for poking around in a namespace.  The
only real missing piece is how to get into the namespace in the first
place.

Would it make sense to add some optional top-level command-line
options to enable this?  For example:

toybox --userns=/proc/whatever/user --uid=x --gid=y

Alternatively, if toybox were to implement nsenter and setpriv, it
would get this for free.  (I own copyright on a large portion of
setpriv, and I would be happy to relicense it.)  Then we could do:

toybox nsenter --whatever setpriv --whatever sh

and it might all just work.

Thoughts?

--Andy