Display revision if post status is pending

It took me a while but I got it! This works as follows:

1. Since you have no reference to the post other than the URI, we segment out the URI to check for a page with that page_name
2. If there is a page, we get the latest revision child
3. Hack the query to force our revision slug to source the page

This works swell because it gives the appearance of a working permalink. It acts as a pseudo permalink.

add_action( 'wp', 'override_404' );
function override_404($query) {

    if(is_404):

        $uri = trim($_SERVER['REQUEST_URI'], "https://wordpress.stackexchange.com/");
        $segments = explode("https://wordpress.stackexchange.com/", $uri);
        $slug_index = count($segments);

        $page_slug = $segments[$slug_index - 1];
        $page = get_page_by_path($page_slug, OBJECT, 'page');

        $revision_args = array('post_parent' => $page->ID, 'post_type' => 'revision', 'post_status' => 'inherit', 'numberposts' => 1);
        $revision = array_shift(get_children($revision_args));

        if($revision):
            $query->query_vars['pagename'] = $revision->page_name;          
            $query->query_string = "pagename={$revision->page_name}";
            $query->request = $revision->page_name;
            $query->matched_rule = "({$revision->page_name})(/[0-9]+)?/?$";
            $query->matched_query = "pagename={$revision->page_name}&page=";
            $query->did_permalink = 1;
        endif;

    endif;

    return $query;
}

The only caveat is sometimes the slug does not save until you publish the page. In order for this to work correctly, the slug must be in the database. Cheers!