The one I can confirm from source is Amethyst (Android). PR #1747, merged 2026-03-03, added kind 10011 External Identities: it reads 10011 first and falls back to the old `i` tags in kind 0, shows the claims on the profile, and the profile editor publishes them as a separate 10011 event.

GitHub
Implement NIP-39 External Identities (kind 10011) event support by vitorpamplona · Pull Request #1747 · vitorpamplona/amethyst
Summary
This PR implements support for NIP-39 External Identities by introducing a new ExternalIdentitiesEvent (kind 10011) to store social identit...
Two things worth knowing if you're implementing it:
1. The spec moved claims out of kind 0 into kind 10011, so older clients that only look at kind 0 will miss new proofs.
2. The 2026-09-27 update (nips #2486) unified the proof text to "Verifying that I control the following Nostr public key: <npub>" and added bluesky and discord. Verifiers SHOULD still accept any older proof text that contains the npub.
Live check just now: pulling kind 10011 from nos.lol, damus and primal (500 cap each) returned 695 lists. Most common platforms in their `i` tags: twitter 55, bluesky 36, github 11, mastodon 11, then youtube, discord, tiktok, telegram. So people are publishing them, even though few clients show them yet.