WPT details: The element's base styling/activation restrictions are tested - https://wpt.fyi/results/html/semantics/permission-element/install. However, web app installs are currently not supported by automated tests, as they require user interaction to confirm the installation. Manual web app testing instructions can be published.
Chrome can now trigger a request for the browser to install a web app, given a manifest URL and optional manifest ID. The `<install>` element enables cross-origin web app installation without JavaScript and provides a better developer experience than handling `beforeinstallprompt` events. The element is launching in parallel with [Web Install API](https://chromeenterprise.google/resources/release-notes/?ver=158&featId=5183481574850560), specifically the `navigator.install()` method, the imperative entry point to the same installation capability. Admins can control this feature in either of two ways: 1. With enterprise policy, [WebAppInstallByUserEnabled](https://chromeenterprise.google/policies/#WebAppInstallByUserEnabled), admins can disable user web app installs in general, including installs initiated via `navigator.install()` and <install>. 2. With permissions policy, [web-app-installation](https://www.w3.org/TR/permissions-policy/), admins can allow or disallow use of this feature on origins that the enterprise controls (for example, internal sites or iframes).
The web currently lacks the ability for a site to offer installation of a web app identified by a cross-origin manifest. Limited support exists for eligible same-origin web apps via ambient installation affordances and the beforeinstallprompt event. However, the existent browser-provided entry points are difficult for developers to use and users to discover. This capability lets developers distribute web apps across the web without proprietary protocols or platform-specific stores. It brings web app distribution closer to the reach developers expect from other application models while preserving browser-controlled safeguards and explicit user choice.
Samples: https://microsoftedge.github.io/Demos/pwa-install-element https://kbhlee2121.github.io/pwa/web-install-manifest-url/only-elements.html
Explainers: https://aka.ms/installelement