iOS app which handles URLs is not showing up in "Open in..." menu (eg. in Safari)

Question

When clicking the 'share' button in iOS Safari (either from the toolbar, or by long-pressing a link), I would like my app to be visible as an "Open in..." option (eg. "Open in News"), so that my app – which is another type of web browser – can open whatever http:// or https:// URL is shared by Safari.

I've registered the document type 'URL' (which I believe is the correct type – please correct me if this assumption is wrong!) in my info.plist file's CFBundleDocumentTypes as best as I can guess from Apple's 'Registering the File Types Your App Supports' documentation, their Technical Q&A, and these related StackOverflow posts 1 2 3:

<key>CFBundleDocumentTypes</key>
<array>
    <dict>
        <key>CFBundleTypeIconFiles</key>
        <array>
            <string>appIcon320</string>
            <string>appIcon64</string>
        </array>
        <key>CFBundleTypeName</key>
        <string>URL</string>
        <key>CFBundleTypeRole</key>
        <string>Editor</string>   <!-- Note: I have also tried 'Viewer' -->
        <key>LSHandlerRank</key>
        <string>Owner</string>    <!-- Note: I have also tried 'Default' -->
        <key>LSItemContentTypes</key>
        <array>
            <string>public.url</string>
        </array>
    </dict>
</array>

I have also written this stub method in AppDelegate.swift (although I think it is in fact irrelevant to the success of this first stage of getting my app to appear as an "Open in..." option):

func application(_ app: UIApplication, open url: URL, options: [UIApplicationOpenURLOptionsKey : Any] = [:]) -> Bool {opening-in-app-getting-uiapplicationlaunchoptionsurlkey-from-launchoptions?rq=1
    print("Received URL: \(url); from source: \(options[.sourceApplication] ?? "nil"); with annotation: \(options[.annotation] ?? "nil")")
    return true
}

... However, my app is still not appearing as an "Open in..." option. I must add that the app icons are correctly bundled with the app, and that the info.plist file opens fine in Xcode, so I can confirm that is not corrupt.

So I have three questions:

1. Having long-pressed on a link and tapped the 'Share...' button, is the document type shared by Safari indeed 'URL'?

2. Having pressed on the graphical button in Safari's toolbar which looks like (confusingly also called a 'share' button), is the document type shared by Safari, as before, 'URL'?

3. Have I written the CFBundleDocumentTypes correctly for a document of URL type? Or if Safari shares something else, what is it (and how should I write it)?