I don't use messengers with vendor lock-in. Therefore Matrix and XMPP see: https://www.messenger-matrix.de/messenger-matrix-en.html
Both self hosted on a Raspberry #freedombox https://freedombox.org/
Matrix has all the features like Slack and WhatsApp and XMPP Conversations: the very last word in instant messaging.
For small projects I like https://uberspace.de/en/ and for something more professional https://www.netcup.com/en
Both have tutorials and labs explaining how to install wordpress and so on.