Allow 3rd party browsers to mint WekAPKs on Android

[FormularSumo]

Description

Since 2017, Android has supported installing web apps as WebAPKs. This allows web apps to be more deeply integrated into Android, for example being included in the app drawer, app search and app pages in settings (including battery, screen time, storage, etc). It also removes the browser badge otherwise shown over the app icon. For a web app to be seen by a user as a "proper" app, that can be compared with native apps, it's crucial that they be installed as a WebAPK to enable this 1st class app functionality.

Currently however, WebAPKs can only be minted (created) by an app store. Chrome uses the Play Store to do this, and Samsung Internet uses the Galaxy Store on Samsung devices. The Play Store method though is hard-coded to only work with Chrome, and Google have provided no public information on how 3rd party browsers would be able to implement this. The WebAPK website has said the following since 2017:

"I am a developer of another browser on Android, can I have this seamless install process? :
We are working on it. We are committed to making this available to all browsers on Android and we will have more details soon.

https://web.dev/articles/webapks

Other browser vendors including Microsoft, Samsung (for non Galaxy devices), Brave, and Kiwi Browser have all expressed interest in implementing WebAPKs in the Chromium issue tracker, but are currently unable to until Google provides a way for them to.
https://issues.chromium.org/issues/40195497

Outcome

At the very least

• Google must open their WebAPK minting server (Play Store) to 3rd party browsers with the same functionality as Chrome already uses, and provide public information on how to use it.

Ideally

• WebAPK installation should be separated from minting servers and instead built-into Android so that browsers are able to install WebAPKs by themselves, regardless of whether Google Play or other specific apps are installed, as currently happens on other operating systems such as Windows.

Any solution should account for how many users the update could reach depending on what is possible via Android/Play System updates or GMS.