It does fire, but we are unable to redirect to the app.

Thanks for the report. Can you elaborate on what you mean by "unable to redirect to the app"?  Perhaps a reproduction / test case would help us understand what exactly you mean?

We are trying to get a user to install our app via 'add to home screen' as
follows:

User navigates to any path on our app  (https://swipesho.weiljones.com)
Js dialog prompts user to either get native app (link to play store) or to
'add to home page'
When clicking 'add to home page' android prompt fires and app is added to
home screen
*At this point we would like to open the current url in the standalone app*

This is what I am doing right now:
On window.appinstalled I am launching another js dialog with "OPEN APP'
action.
When user clicks we do: open.window(location.protocol + '//' +
location.host + location.pathname', '_blank') in order to circumvent the
popup-blocker
This opens the app if user navigated to the root i.e
https://swipesho.weiljones.com.
However, if the path is not root chrome opens another tab :/
In the app manifest both scope and start_url are set to '/'.

Perhaps I am missing something entirely here, but the goal would be someone
clicks on a link, opens the site in chrome, clicks on 'add to home screen'
and finally gets redirected to original path in the standalone app :)
Hopefully there's a more elegant solution.

Cheers,
David

Hmm. Instead of window.open could you just do a navigation of the top level window (e.g. treat is a link click). Because intent filters have changed and the navigatoin is now in scope of an installed app, I would think this would trigger our logic to then open the app