Ok, I found out how to do this myself. It requires the following changes and I’d be glad to have them added.
In acf-input.js #5307:
$.each(location.address_components,function(key,item){
if (item.types[0] == 'country') {
acf.val( self.$el.find('.input-country'),item.short_name);
}
});
Another change goes to google-map.php #84 ,the array gets one more entry after lang
:
'country' => ''
These small changes add the short_name of the country to the saved data.