It runs on any old raspberry pi (any but raspberry pi 1 I believe) in your house, can be used by family and friends as well. Has iOS and Android apps… I have had good experiences with the easy to set up https://snikket.org/ XMPP server.

what do you have in mind? Jabber/XMPP is very similar.

But it has 10k impressions!!! which means that 9k bots scrolled past it and a couple of people had it loaded on their app.

Why and where would this be useful?

Meh not sure I would want that.