I've used the getLatestCommit endpoint on the old relay to check if a given DID or PDS is "federated with" the Bluesky infra, since it was returning commit info for known DIDs and errors for DIDs that were not recognized for whatever reason. This endpoint seems to be MIA after the migration to the non-archival relay last month.
As discussed here with @bnewbold: https://bsky.app/profile/mackuba.eu/post/3lbusevmrak2o
I've used the getLatestCommit endpoint on the old relay to check if a given DID or PDS is "federated with" the Bluesky infra, since it was returning commit info for known DIDs and errors for DIDs that were not recognized for whatever reason. This endpoint seems to be MIA after the migration to the non-archival relay last month.