

Don’t host the calendar, just host some WebDAV/CalDAV. That format is supported by basically all apps on every platform (usually including the default app on most phones), so everyone can pick what they want (or just stick with what they already use).
My personal pick for that purpose is Radicale.



I’m using the default calendar app that a long time ago came with that lineageos install.
Should be this one iirc…