Nosta now shows external identities (NIP-39). You can see an example here, where someone has linked their Twitter account.

https://nosta.me/npub1nm9mpe60ve0zd2qjcs2j2ruhrq44sqdjvz9zat80wucgyp4t0sys0dmsfn

Have you linked GitHub, Mastodon, or Telegram accounts or know someone who did? Would love to know for testing.