Better contact integration on Linux

[SethFalco]

This feature request is an extension to:

• Better contact integration on Android and iOS #1066

I just want to ask that Linux not be forgotten. Many communities and companies have been considering Linux on mobile for a while, and with projects like postmarketOS and the PinePhone going well, there are users such as myself that actually daily drive Linux instead of Android or iOS.

I would appreciate it if this option could be explored so that we can, for example, sync contacts with GNOME's Contacts app, or KDE's KAdressBook.

KAddressBook stores all the personal details of your family, friends and other contacts. It supports large variety of services, including NextCloud, Kolab, Google Contacts, Microsoft Exchange (EWS) or any standard CalDAV server.

— KAdressBook - KDE Applications

Alternative approaches may include allowing users to opt-in for syncing to/from (CardDAV) providers/clients. By either supporting CardDAV itself, or supporting syncing with something that does, like Nextcloud. This would enable users to utilize existing tools to handle the integrations.