Ask HN: What service to use as a contacts/calendar server?

I'm trying to go through the de-Googling process.

I have used ProtonMail and Signal for a few months and love it so far.

I'd like to move my contacts and calendar away from Google.

ProtonMail offers contacts, but they don't integrate with other apps on Android (maybe I just use it anyway?)

I've read about EteSync [1], which allows for end-to-end encrypted contacts and calendar. However, I'm not sure how comfortable I am with trusting that a project of that scale implements cryptography correctly[2] (no offense @tasn)

Maybe NextCloud?

What does the HN community use to store contacts/calendar?

[1] https://www.etesync.com/ [2] https://git.io/fhpaP