I much appreciate commentary so far.

Sounds like best knowledge is that we're not there *yet*.

And, yes, I have tried emacs --eval ..., even emacsclient --eval (BTW I run emacs (and emacsclient :-) via a perl script).
Unfortunately, perl6-debug does not (yet) seem to output information that emacs gud logic uses to make it behave as expected (:-(.

I am sure this will come, and am (of course) willing to help, and will be on the lookout for perl6db.el, or some such.
And I'm sure we'll get there. Emacs is a great environment for debugging perl, and will be no less so for perl6.

Thank you.