It's an interesting idea.
At the end of the day though, all chunks and snippets are meant to output something. So it seems you may have to call a special debug snippet from EVERY other snippet and chunk, and then the debug snippet would collect all the details of each thingy and echo the final tally.
There is no system event that connects to something like "onChunkRender" or whatever so that you could capture them, so a plugin is out. It would have to either be done via the chunks/snippets themselves, or by calling a single master debug snippet to collect the pieces.
In your chunks you could have a call like
Then the snippet would collect all the comments and stick them in the final output or something.
Only problem is the comments would all appear together.
If you want the comments to appear exactly in code where the chunk's output is rendered, then I would guess it has to be the chunk itself that does the outputting.
Anyway, good luck finding a solution!
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