web app manifest includes key pieces of information required to make your app installable.
Lighthouse flags pages that don't have a web app manifest that meets minimum requirements for installability:
If a page's manifest doesn't include the following properties, it will fail the audit:
iconsproperty that includes a 192x192 px and a 512x512 px icon
displayproperty set to
prefer_related_applicationsproperty set to a value other than
Caution: A web app manifest is necessary for your app to be installable, but it isn't sufficient. To learn how to meet all the requirements for installability, see the Discover what it takes to be installable post.
In the Lighthouse report UI the full PWA badge is given when you pass all of the audits in all of the PWA subcategories (Fast and reliable, Installable, and PWA optimized).
Make sure your app has a manifest that meets the criteria above. See the Installable collection for more information about creating a PWA.
When your app meets the minimum requirements for installability, Chrome fires a
beforeinstallprompt event that you can use to prompt the user to install your PWA.
Try it! Learn how to make your app installable in Chrome with the Make it installable codelab.
Other browsers have different criteria for installation and for triggering the
beforeinstallprompt event. Check their respective sites for full details: