Suppose I want to find all notes with the property "prop-name".

I think org-map-entries can do this but I'm having problems working out how properties work.

The documentation talks about a "MATCH" parameter but offloads the documentation to org-agenda, which I'm finding difficult to understand or call programmatically. I think this looks like the relevant documentation.

MATCH is a tags/property/todo match as it is used in the agenda tags view.
Only headlines that are matched by this query will be considered during
the iteration.  When MATCH is nil or t, all headlines will be
visited by the iteration.

I think be something like (org-map-entries (lamdba (x) x) "prop-name={.*}").