Are there any independent projects implementing the AT protocol?
There's an (incomplete) list here: https://docs.bsky.app/showcase
And the protocol is documented here: https://atproto.com
My question was motivated by the fact that from the outside the AT proto ecosystem looks pretty monocultural, and personally I don't trust that. :)
Basically, you're right, but just because you're asking early on. This is about to change real quick.
I'm contrasting this through the prism of having seen people implementing ActivityPub software as early as 2017, when it was merely a draft and everyone was complaining about how many things had been left out.