Ask HN: Good self-hosted calendar sync framework?

I'm recently trying to de-cloud myself. On the top of my list are email, calendar, and meetings since I feel like all this remote work is really tying me into these cloud-based solutions.

I've found some neat libraries regarding email and WebRTC meetings but I can't find anything on calendar sync for the life of me. I have a UI in mind for my own calendar app but I can't find a good open source framework or library that does calendar sync with both Google Calendar (personal), Office365 (work), and CalDAV (also work).

I've found a library that (kind of) does Google Calendar by itself and a slew of projects regarding Office365's API that don't really seem to have much in the way of reliability. Haven't found anything in the way of CalDAV.

Hoping someone can recommend a good calendar sync framework, preferably with JS or Rust bindings?