I made the simplest implementation of #ActivityPub C2S protocol in #AndStatus, allowing me to log into pleroma.site, read home timeline and get other user's info (i.e. read the Actor's profile based on his "id").
But I've got an error response from pleroma.site server on an attempt to send a Note, so I created another bug report in pleroma issues tracker: https://git.pleroma.social/pleroma/pleroma/issues/650

Alpha build of AndStatus is attached to this comment: https://github.com/andstatus/andstatus/issues/499#issue-389014088 , source code is available in the repository. https://loadaverage.org/attachment/5020018