Check out @steve on #SocialHub with a proposal to work on #ActivityPub #C2S, the client-to-server Social API part of the #W3C Recommendation.
The Social API didn't get much uptake on the #Fediverse where generally the #Mastodon API is used (and abused) for client/server communication.
It is not because the Social API isn't good, just that no one ever did the legwork to mature this part of the spec.
Are you interested in C2S and help push the #SocialWeb?
More info:
https://socialhub.activitypub.rocks/t/nextgen-activitypub-social-api/4733