I noticed the following issues when trying to sign in and add an instance with my accounts on Lemmy and Piefed instances (lemmy.ca/u/otter and piefed.ca/u/otter specifically):

Logging in

Signing in with the profile-description (bio) code works on both Lemmy and PieFed, but logging in with a DM does not work for either.

On Lemmy, I get the error message

We could not deliver a message to that account. Check the handle, or use another way to sign in.

Meanwhile on Piefed, FediDB says that it sent the code, but it fails silently since I never receive a message on the account. I looked into adding fedidb.com as a trusted instance from the admin side, but I don't think that's the issue since there are no entries for fedidb.com there at all.

I know it should be possible to receive DMs from non-threadiverse instances since Canvas used that for auth. If it helps, here is the source code for that project:

I think they do it by sending the DM as both a Mastodon style note and as a Lemmy style chat message (link to code)

// around line 144
   const outbox = [
      await message.build(fedify.Note),
      await message.build(fedify.ChatMessage),
    ].map((obj) => apub.prepareObject(obj, ts));

Admin verification

This one fails for both.

On Lemmy I suspect it is looking at the wrong endpoint since I get this:

Could not reach the server to confirm your admin status.

Meanwhile on Piefed, I see the following message despite using an admin account that shows up in /api/alpha/site

Your account is not an admin or the contact account of this server.

I haven't tried the other methods yet :)