Thanks for the responses. I know there are multiple tools out there (to wit, Wes's response), but I'm really after what people actually use and find works. I apologize that wasn't clear. I did neglect to mention that my environment is Linux (specifically Ubuntu 18.04), so Windows-based solutions aren't likely to be workable for me.
For the time being, I've been working through one or two of the docs/tutorials about the parsing/compiler internals which focus on the C side, so gdb with curses display enabled (Ctrl-X a) and built-in PyObject support has been sufficient. I will eventually need mixed language debugging though. And, as an Emacs user, how this might play in that sandbox is of interest.
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