We have the XMPP Compliance Suites 2018[0] providing an overview of protocol-level specifications that a modern client or server should implement, and there was recently a nice article[1] for some example use cases.
What is still missing is everything above the wire protocol level. The XSF, being the XMPP Standards Foundation, is guarding the protocols, and things like UX and client interoperability are considered as off-scope. However, there are people interested in these topics as well looking for fresh collaborators.
That looks pretty cool. Maybe I should ask SamWhited why they didn't include OMEMO, Audio and Video Calls as features as he is writing in this thread too :D
What is still missing is everything above the wire protocol level. The XSF, being the XMPP Standards Foundation, is guarding the protocols, and things like UX and client interoperability are considered as off-scope. However, there are people interested in these topics as well looking for fresh collaborators.
[0] https://xmpp.org/extensions/xep-0387.html
[1] https://www.erlang-solutions.com/blog/21-xmpp-use-cases-and-...