Thanks all for your input. It's a bit buffling that calendars are not a solved problem in 2021. Going down the path of vdirsyncer + davmail with some self writt

Thanks all for your input. It's a bit buffling that calendars are not a solved problem in 2021. Going down the path of vdirsyncer + davmail with some self written filters to only show blockers (stripped everything else out) seems to be the most sensible way.