Filter Admin Lists by Any Taxonomy

// Taxonomies that should not get a dropdown (WordPress already shows one for post categories).
$wpide_tax_filter_skip = array( 'category', 'post_format' );

add_action( 'restrict_manage_posts', function ( $post_type ) use ( $wpide_tax_filter_skip ) {
    foreach ( get_object_taxonomies( $post_type, 'objects' ) as $taxonomy ) {
        if ( ! $taxonomy->show_ui || ! $taxonomy->query_var || in_array( $taxonomy->name, $wpide_tax_filter_skip, true ) ) {
            continue;
        }

        $selected = isset( $_GET[ $taxonomy->query_var ] ) ? sanitize_title( wp_unslash( $_GET[ $taxonomy->query_var ] ) ) : '';

        wp_dropdown_categories( array(
            'taxonomy'        => $taxonomy->name,
            'name'            => $taxonomy->query_var,
            'value_field'     => 'slug',
            'selected'        => $selected,
            'show_option_all' => $taxonomy->labels->all_items,
            'hierarchical'    => $taxonomy->hierarchical,
            'hide_empty'      => false,
            'hide_if_empty'   => true,
            'show_count'      => true,
        ) );
    }
} );

// The "All" option submits 0; drop it so the list is not filtered by a term called "0".
add_filter( 'request', function ( $vars ) {
    if ( ! is_admin() ) {
        return $vars;
    }

    foreach ( get_taxonomies( array( 'show_ui' => true ), 'objects' ) as $taxonomy ) {
        if ( $taxonomy->query_var && isset( $vars[ $taxonomy->query_var ] ) && '0' === (string) $vars[ $taxonomy->query_var ] ) {
            unset( $vars[ $taxonomy->query_var ] );
        }
    }

    return $vars;
} );