This would have been great about 5 years ago, and still would be useful, but I think we're going in the direction of unified protocols, like ActiveSync, JMAP, MAPI/EWS etc.
IMHO x-DAV should have been there from day one. I'm using SOGo for my family's groupware and although SOGo provide plugins for Thunderbird, I've been missing an integrated, seamless approach.
I used to use SOGo but found it used way too much resources. None of us really even used 'webmail' so I ditched SOGO.
I went with https://radicale.org most of my family either uses mail clients, Thunderbird, (with Lightning), Canary Mail (the mac user), DAVx⁵ (formerly Davdroid). Radicale allows for ldap authentication which was a must for us.
On a side note the SOGO Integrator plugin took AGES to be updated for Thunderbird 60. I found https://gitlab.com/CardBook/CardBook/ to be WAY better, particularly as it replaces the crufty-old Thunderbird addressbook.
I've wanted to use z-push with a PSQL backend for a while, mostly to cut off gmail and repatriate my email archives
SOGo being written in obj-c means it's fundamentally much better suited to this task.