In KDE's online accounts system (which is based on https://gitlab.com/accounts-sso) we have the ability to log into your Nextcloud account (https://invent.kde.org/network/kaccounts-providers/-/tree/master/plugins/nextcloud-ui). That does things like adding a shortcut to Dolphin, allows contact synchronization via Sink and hopefully in the future integration with KDE PIM. What it currently does not do is integration with the official Nextcloud client. Let's fix that :)