Right! Sadly we don't have access to native/origin fediverse accounts' AP actors, we can't set or change fields on them. Same with native/origin Bluesky accounts' DID docs and profile records.

Right now, you can see if someone is bridged by fetching their Bridgy Fed user page – eg https://fed.brid.gy/web/snarfed.org for a web site, https://fed.brid.gy/ap/@snarfed@indieweb.social for a fediverse account, https://fed.brid.gy/bsky/snarfed.bsky.social or https://fed.brid.gy/bsky/did:plc:3ljmtyyjqcjee2kpewgsifvb for Bluesky – and if it returns HTTP 200, they're bridged.

Not ideal. We'd love a better way eventually! For now, I'll add this to our docs.