Page summary gets coordination information from MW action API.
This is implemented in this extension:
https://www.mediawiki.org/wiki/Extension:GeoData

We need to add this extension as a dependency to our extension:
https://www.mediawiki.org/wiki/Manual:Extension_registration -> Requirements (dependencies)

Then we can fetch the required coordinates for summary using this function:
https://gerrit.wikimedia.org/g/mediawiki/extensions/GeoData/+/3e6fd020e97eba57e5e1d4643d485a6fa849f6cd/includes/GeoData.php#14