There is movin, written in php
In what topics would the caldav5 not being able to fullfil the needs?
Third, it also has basic personal and business financing built-in and integrated with the project management features. For example, you can have tasks related to bills and spending,
Don't we have a chatroom thing in Hubzilla already? Maybe this could be a start for an XMPP client built into HZ (just guessing, really)
That is a challenge
How does that work exactly?