Recently, a feature has been implemented to allow verification of Mastodon account via a Keyoxide url to a profile containing the OpenPGP fingerprint. Another feature has been sugested in another issue by @KubikPixel to verify the Keyoxide profile on Mastodon. This is done by adding the anchor tag to the webpage that is being verified like this one.
<a rel="me" href="https://mastodon.technology/@dusansimic">Mastodon</a>
I thinks this could be done since we are already verifying the proof and we could just add the tag to the document once it’s verified. I would show a green checkmark next to the Keyoxide profile url.