Hi,
what mean you, have got Hubzilla and Riseup synergy-potentials?
What is Hubzilla? - https://hubzilla.org/help/about/about_hubzilla
Hubzilla-Features - https://hubzilla.org/help/about/about_hubzilla#Features
Hubzilla History - http://www.talkplus.org/blog/2016/the-history-of-hubzilla/
And see too Hubzilla-homepage https://hubzilla.org
And see too Hubzilla-Homepage https://hubzilla.org/hubzilla/ too
And see too Hubzilla-Homepage https://hubzilla.org/ too
Interesting! We'll have a look at it, and see if it is something we can participate in!