Ah you're referring to the fqdn of an instance from a browser.

Those aren't "Lemmy links". As Lemmy has its own linking system like in my examples.

The issue at hand is there are potentially hundreds if not thousands of cases to catch for this feature to work the way you'd hope. As there's no standard url format to enroll or authoritative list of instances to be enrolled that would satisfy Google.

It may be possible for the various web developers maintaining the various webuis to make it easier.

https://developer.android.com/training/app-links

You could try submitting a feature request with the different webui projects out there and see if they will resolve it or better explain why they can't.