Google Calendar

Mobile sync with Apple Calendar

Most of the time when adding a new calendar to Google Calendar, and you don't see it showing up on your Apple calendar (iOS/iPadOS/macOS), the reason might be that the calendar is not selected for "syncing". Visit this arcane page to fix it.

Webcal URLs doesn't sync events

If you want to subscribe to a calendar which URL starts with webcal:// and you notice it won't sync, try replacing webcal:// with https://.