Process attachment does not work with JSON output / sub-second sampling does not work with STDOUT output

[JJ]

When I try this command line:

sudo scaphandre json -s 0 --step-nano 1000000000  -p $!  

I get this error:

error: unexpected argument '-p' found

Fair enough, it's not included in the reference. But then if I try to use sub-second sampling with stdout exit (which is the main feature I'm looking for, actually)

sudo scaphandre stdout -s 0 --step-nano 1000000000  -p $! 

(I don't know if this would work with JSON output, to be honest)

I get a different error:

error: unexpected argument '--step-nano' found

  tip: a similar argument exists: '--step'

Again, fair enough, since it's not in the reference. So the issue is: can I get sub-second sampling and attachment to a process with some output filter?