Does anyone know why there's no desire to see a working standard (protocol) for calendar/tasks?
It's clear that CalDAV doesn't function consistently across devices (and does seem to be dying as a standard). If you work across different devices/OS it's virtually impossible to get things set up seamlessly. Companies and developers of task apps seem happy to create silos and not look at interoperability.
If you want to self-host, it's too hard to do this and you really are limited to a tiny number of options.
zero-hassle setup in Thunderbird for both of those things
DAVx on Android works seamlessly for calendar and contacts Sync
Fossify calendar to view, edit calendar
default contact app for contacts
Infcloud as a web frontend for Radicale. Not pretty, but absolutely functional (and I hardly ever need it thanks to Android calendar app / Thunderbird)
Haven't tried todo lists yet, but I would imagine they are similarly hassle-free.
The only annoyance I have is that DAVx is required at all, but I'd suspect that's an Android/Google issue? IDK.