Nextcloud and CalDAV

It’s not the same as was raised there, but is definitely related. And it’s comments in that thread like this:

that make me say the devs are treating Nextcloud like a second-class citizen in this regard. And the mention of:

…still hasn’t happened five months later. As of now, there’s no supported/documented way to make Nextcloud work the way it’s supposed to. I’m happy to document it if I can figure out how to do it, but Apache config changes that seem like they should do what I need, don’t, and the server logs don’t seem to be helping track down what’s going on. Where do I look from here?