Chrome for Android started adding these features between Chrome 61 and 75. In Chrome 89, web sharing is available on Windows and ChromeOS, while registering as a share target is supported on ChromeOS. On these platforms, sites can now use navigator.share() on desktop to trigger a share dialog box. And an entry to the web app manifest allows a PWA to act as a share target.
For information on web sharing, see Integrate with the OS sharing UI with the Web Share API. To learn to configure a PWA as a share target, see Receiving shared data with the Web Share Target API.
To quote Chrome 89 blog
See also https://github.com/pageboard/client/issues/16