Feature Request: Enable CalDAV and CardDAV independent of Nextcloud

However, there does not appear to be a way to connect to a CardDAV and CalDAV provider outside of Nextcloud (in my case, I use Fastmail). It would be nice to have those features broken out, so one can access a CardDAV and CalDAV provider independent of Nextcloud. Nextcloud allows use of contacts and calendar through CardDAV and CalDAV, so the underlying functionality is present within GNOME, there just needs to be the GUI option added.