There's no citekey variable in Zotero (not counting in the new Preprint item type), so, no. When all fields gain a Citation Key field, we can consider it.

Annotation citations already include the page label of the annotation.

I strongly support having a citekey variable matching the Citation Key field. That would help for note template on the one hand, and for configuring the lookup engine to get the exact paper in our field from the https://inspirehep.net/ database after pinning the Citation Key to inspire-hep using BBT.

Would this require a Zotero change or a CSL change?

Just a Zotero change. CSL has citation-key as of 1.0.2

This is just an implementation question; the addition of a citekey variable in Zoter has been decided/planned for quite some time; implementation isn't trivial but will happen alongside the other item type & field changes (which, as I understand it, will happen bit by bit).

FWIW, I have basically no private communication with Zotero devs, so everything I know is based on public communication. The only exception I can think of was an alpha preview of ZotBib on which I provided feedback some years ago.
(For CSL, we very occasionally do email amongst a small group of maintainers -- not including Zotero devs -- but that concerns organizational questions; all substantive decisions happen publicly).

I developed a workflow with an apple script, using the Automator App on Mac, that runs after a shortcut, and that changes the format of an annotation I copy in Zotero's pdf-reader. Perhaps someone who comes to this page is interested and can use and adapt it to their needs.
It changes the default format “This ist the quote” ([Autor, Year, p. page](Link-to-item)) ([pdf](Link-to-annotation)) to *“This is the quote”* [@Autor-Year, page]-[pdf](Link-to-annotation), which gets close to the citekeys I need, to use Pandoc in Obsidian more seamless.


-- get content from the clipboard
set theClipboard to the clipboard

-- extract quote
set quotedText to do shell script "echo " & quoted form of theClipboard & " | awk -F '“|”' '{print $2}'"
-- PAUSE set quotedText to do shell script "echo " & quoted form of theClipboard & " | awk -F '\\(\\[' '{print $1}'"

-- extract author
set authorRaw to do shell script "echo " & quoted form of theClipboard & " | sed -n 's/.*(\\[\\([^,]*\\), \\([0-9][0-9][0-9][0-9]\\), p\\. \\([0-9]*\\)\\].*/\\1/p'"
-- delete brackets in the beginning & second authors & et. al
set author to do shell script "echo " & quoted form of authorRaw & " | sed 's/^[\\[]//; s/[]]$//' | awk -F ' and' '{print $1}' | awk -F ' et al' '{print $1}'"

-- extract year
set pubYear to do shell script "echo " & quoted form of theClipboard & " | sed -n 's/.*(\\[\\([^,]*\\), \\([0-9][0-9][0-9][0-9]\\), p\\. \\([0-9]*\\)\\].*/\\2/p'"

-- extract page
set page to do shell script "echo " & quoted form of theClipboard & " | sed -n 's/.*(\\[\\([^,]*\\), \\([0-9][0-9][0-9][0-9]\\), p\\. \\([0-9]*\\)\\].*/\\3/p'"

-- extract pdf link
set pdfLink to do shell script "echo " & quoted form of theClipboard & " | awk -F 'open-pdf' '{print $2}' | awk -F '[)]' '{print $1}'"

-- combine the extracted elements to the new format
set formattedAnnotation to "*“" & quotedText & "”* [@" & author & "-" & pubYear & ", " & page & "]-[pdf](zotero://open-pdf" & pdfLink & ") "

set the clipboard to formattedAnnotation

display notification "Annotation successfully formatted and copied to clipboard" with title "Zotero Annotation Formatter"