Not all apps necessarily register an URL Scheme, but there’s a workaround yet again with the Shortcuts app.
Create a new Shortcut (not an automation this time!) and add the “Open app…” action. Select the app you’d like to add here.
At the top, give the Shortcut a name, like “Open Yahoo Finance”.
In one sec, proceed to add a custom app like you’d usually do. The trick is now, we are using the URL Scheme of the Shortcuts App to run the Shortcut we’ve just created.
The URL Scheme contains a URL parameter at the end called “name=…”. Insert the name of the Shortcut you’ve just created.
Please note: replace all spaces contained in the name with %20