I would like the KDE Calendar widget to display the calendar events from my egroupware calendar (Caldav) which I have configured in Thunderbird. The server uses TLS client certificate authentication which is not supported in KOrganizer, even though well voted for respective bugs exist since 2006. Therefore, I cannot directly connect the calendar to KOrganizer.
PS: Kubuntu 21.10, Plasma 5.22.5, Thunderbird 91.5, but all this should be rather irrelevant
Update 1: I have managed to create an .ics file calendar in Lightning that is accessible to KDE. if someone tells me how to synchronize locally two calendars in lightning that would be a complete solution. Alternatively, if I could automate exporting from Lightning to an ics file (overwriting the old one), this would also be a complete solution.
Update 2: On gnome there is this fantastic thunderbird add-on: https://addons.thunderbird.net/en-us/thunderbird/addon/eds-calendar-integration/reviews/
