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>...there are a few good Cal/CardDAV options

Such as? I've been looking for some...

>I also find PHP applications incredibly frustrating compared to more simple tools.

Really? I find them so much simpler, just stick everything in a folder and point Apache at that folder. No messing about with extra layers like docker.

[encryptluks2]

Xandikos, but it only supports single user last I checked. Radicale and others. There is a list of Cal and CardDav software on Wikipedia.