Add taxonomy to a WordPress post type as a filter. See https://gist.github.com/koskinenaa/86fd3acd75959e9aa0635ce00934e26c for multiple post types and taxonomies

wordpress-filter-custom-post-type-by-custom-taxonomy.php

public function filter_post_type_by_taxonomy( $post_type, $which ) {

    if ( 'my_post_type' == $post_type ) {
      $taxonomy = get_taxonomy( 'my_taxonomy' );
      if ( $taxonomy ) {
        // Retrieve taxonomy terms
        $terms = get_terms( $taxonomy->name );
        // Display filter HTML
        echo "<select name='{$taxonomy->name}' id='{$taxonomy->name}' class='postform'>";
        echo '<option value="">' . sprintf( esc_html__( 'Show All %s', 'text-domain' ), $taxonomy->labels->name ) . '</option>';
        foreach ( $terms as $term ) {
          printf(
            '<option value="%1$s" %2$s>%3$s (%4$s)</option>',
            $term->slug,
            ( ( isset( $_GET[$taxonomy->name] ) && ( $_GET[$taxonomy->name] == $term->slug ) ) ? ' selected="selected"' : '' ),
            $term->name,
            $term->count
          );
        }
        echo '</select>';
      }
    }
  }
}

add_action( 'restrict_manage_posts', 'filter_post_type_by_taxonomy' , 10, 2);