One of the funny things about ActivityPub is that we originally had a charter to develop a social API, with an option to make a social federation protocol.

The ActivityPub federation protocol has been very successful. The API is only implemented in a few projects, which I think is a mistake, but I hope to see improve over time.

Some people think the API drags down the federation protocol, without realising that the protocol wouldn't exist without the API. 

 @77ba84fb is the API you''re referring to here basically the C2S portion of the protocol? 

 @77ba84fb AFAIR, Pleroma tried to implement the native AP API, like, a century ago.

Not sure if any clients did, though.