Matrix servers are now fairly simple to deploy.
https://www.youtube.com/watch?v=dDddKmdLEdg I do wish the Element team moved a bit quicker at attacking Slack head-on. Element isn't super polished yet nor does it implement all the features built into the server/spec. So there is some catching up to do there. But the project is more than ready to use today at a large org and it includes a ton more features than what you get out of the box with an off the shelf XMPPd.
https://joinup.ec.europa.eu/collection/open-source-observato...