Why not just host your own Nextcloud Talk, they are also using ActivityPub for federation between Nextcloud instances and are rumored to be working on a socnet plugin to connect to GNUS/Postactiv/Mos type federation so you can host your own.
@geniusmusing #NextCloud is planned to be part of the next generation of FOS (family online services), but the whole thing will have to wait until I have *time and energy to set it up (unless I can persuade #sonOne or @amic to set up and run it).
* time and energy — I was discussing (on #Wire) the greatly reduced energy and motivation that three years plus of travel and overtime has brought with #sonTwo and #Daddy_A and @amic earlier today.
@geniusmusing #Wire is currently not #federated (though the client and possibly the server are now FOSS), but it offers an easy noob-friendly encrypted chat. Out of the ones I’ve tried, this is the one that I’ve been able to get some of my family members to use. (Some of them also used #Ring, but there were some problems with a version upgrade forcing people to re-request connection to their contacts, and none of my contacts made it past that.)
@lnxw48a1 Signal's visible distrust of others and deep reliance on its own systems makes it a shockingly vulnerable system to correctly applied pressure. De minimise, it should have both federation and true Linux client support (not Chrome extension or w/e)... Oh well.