Anyone thinks this should not work? I can’t make it work for some reason.
add_action( 'wp_head', function() {
switch_to_blog( $blog_id );
wp_query( 'p=' . $post_id );
});
The point is that instead of displaying whatever page I am about to display, I choose content from a different blog instead.
For other people with the same issue who don’t read comments the solution was to change the hook from
wp_headtoget_header