Follow along with the video below to see how to install our site as a web app on your home screen.
Примечание: This feature may not be available in some browsers.
https://www.google.com/search?q=мультиязычный+сайт+php
Скорее всего нужно прийти к /en /ru /ch в url.
site.local/index.php?lang=en
switch ($_GET["lang"]) case "en": ...