acf-add-location-rule-custom-post-type-comments.php

/**
* Add a custom location rule for Comment Type
*/
add_filter('acf/location/rule_types', 'THEMENAME_acf_location_rules_types');
function THEMENAME_acf_location_rules_types( $choices ) {
    // This creates a new group in the Location dropdown called "Comments"
    // And adds a child-item called "Comments on Post Type"
    $choices['Comments']['comments_on_post_type'] = 'Comments on Post Type';

    return $choices;
}

/**
* Populate the custom location rule's choices
*/
add_filter('acf/location/rule_values/comments_on_post_type', 'THEMENAME_acf_location_rules_values_user');
function THEMENAME_acf_location_rules_values_user( $choices ) {
    // Get all the "public" post types.
    $post_types = get_post_types(array('public'   => true));
    
    // Assuming there are some, loop through and add to the $choices array.
    if( $post_types ) {
        foreach( $post_types as $post_type ) {
            $choices[ $post_type ] = $post_type;
        }
    }

    return $choices;
}

/*
* Perform the match
*/
add_filter('acf/location/rule_match/comments_on_post_type', 'THEMENAME_acf_location_rules_match_comment_post_type', 10, 3);
function THEMENAME_acf_location_rules_match_comment_post_type( $match, $rule, $options ) {
    global $post;
    
    // Get the post type of the current page, as well as the one we've selected
    $current_post_type = $post->post_type;
    $selected_post_type = $rule['value'];
    
    // Depending on your operator, compare and return a boolean for ACF to use.
    if ($rule['operator'] == "==") {
    	$match = ( $current_post_type == $selected_post_type );
    } elseif ($rule['operator'] == "!=") {
    	$match = ( $current_post_type != $selected_post_type );
    }

    return $match;
}