This is based on a so called "web component" that I built by the way (see https://www.npmjs.com/package/h5p-theme-picker and https://github.com/otacke/h5p-theme-picker). That way it is super simple to add the theme picker to other #H5P integrations such as #Moodle's own H5P integration, #Lumi, the #ILIAS plugin, etc. The extra plugin for #WordPress is tiny - and hopefully redundant one day: H5P Group is welcome to include the H5P theme picker into their WordPress plugin directly, of course.