"What you're refering to as Mastodon, is in fact, AP/Mastodon, or as I've recently taken to calling it, AP plus Mastodon. Mastodon is not a social network unto itself, but rather another free component of a fully functioning AP (ActivityPub) system made useful by the AP standard, shell utilities and vital system components comprising a full social network as defined by the federati."
Me, paraphrasing a known philosopher of Free Software ;)