1. On a Moodle website create a URL resource in a course. It can link to any website.
2. On the Moodle Mobile app and navigate to the URL resource.
3. When you click on the resource it opens a browser and directs you to your Moodle resource address (www.website.com/mod/url/view.php?=1234). You'll then have to log into your Moodle website to access the External URL.

I think the app should have direct access to the External URL and not it's resource url.

In the app, when you click the "i mark" it should say;
Name
Viewable on this app: Opens in browser
Description (if present)
External URL (not the Moodle resource address that the app currently shows)

I tested this on Android (Mobile) and iPad.