I have just added a CoTech shared address book and CoTech shared calendar to the Nextcloud server — if people link their devices that support contact lists and calendars (for example phones and any CalDav clients, typically email clients) to these then it could be useful…
It would be great if other people could also add their own contact details.
I have just set up the Nextcloud client and DAVdroid from F-Droid on my LineageOS Android phone and it all seems to be working well