Posting an example on what I did in lieu of a standard-ish way to modify Mastodon code that could be updated and removed on any updates.
I created a super simple “me.html” page with a redirect to the Mastodon URL on the /public root path of the Mastodon instance in linux like this
<!DOCTYPE html>
<html>
<head>
<title>Owner Validation Page</title>
</head>
<body>
<a rel="me" href="https://self.social/@mergy">Jonathan Mergy</a>
<script>
let url = "https://self.social";
window.location.href = url;
</script>
</body>
</html>
This causes the validator to go there and at least gets me a green on my profile if you use the root URL + /me.html and Mastodon is happy.
