We had a similar idea in the designs for the Experience Space in Sites 9.5 but opted to de-scope work for now. I think a good fit would be to simply show the hyperlink, possibly while an item is in "read-only" mode, letting the user see, copy, or otherwise click on such external links.
To be sure, what is the specific use case you were looking to address for this? Is the idea to be able to quickly visit the URL to do something there? Are you trying to share the URL with someone else? Or is this perhaps about making sure the link works? "Visit" could be a solution, but perhaps "Copy location" (suggested by Ron Grisnich) might be a better fit, or a "valid link" icon, or even something like the "Send to" options from the Classic UI.
More context and votes can help guide both a possible solution and priority for this idea.