@freemo I use my onw Nextcloud Calendar next to Proton Calendar.

@freemo I'll be watching this thread. I've de-Googled myself almost completely. One of the problem areas is Calendar, where I maintain calendars that are shared with up to 20 people, most of whom are not computer people and barely know how to use a smartphone.

@freemo A real paper based calendar?

@freemo An actual calendar that I put misleading information on, a small notebook with the information mixed in with nonsensical rambling and pictures of things. It takes all three to put it together.

I'll set alarms on my smartphone at the wrong time and label them the wrong thing.

For you, I'd recommend a picture and NFC tag that stores a key. You just embed a photo with a bunch of encrypted information and use a Yubikey to decrypt it. You can do the same with Wav files and then embed that. The NFC tag should just link to a website that lets you know who touched it.

@freemo I've tried a couple. Etesync is one of the best (it's a paid, open source e2e-encrypted service), but I found it hard to share calendars (e.g. for virtual assistants), so now I use Proton.

Radicale is also pretty good (self-hosted, open source & e2e-encrypted). But since I like to go offline frequently I found it hard to keep my calendars synced.