Well, I meant adding activitypub to apps, not machines, but... say the juicer can somehow recognize ingredients put in (machine vision or just by being told by a user through an interface). When you juice it posts the juice you made + achievements (30 days juicing straight! Very green!). Followers add comments, favorite, follow or reshare/boost and encourage each other to improve their health through juicing?
Main reason for me doing my own thing is that I have a specific vision for what I'm making that's closer to Ghost or WordPress rather than Medium.