It would be nice if everyone had the same equipment at home and could therefore use the same possibilities and options. But unfortunately it doesn't work that way. An annoying consequence of this is that anyone who uses Google Calendar will not be able to sync it with the iCloud calendar. Fortunately, as always, there are tricks for that.
There are several ways to make Google and Apple's calendars work together, but most of them require an app. There is an app for Android (ICalSync2) with which you can import an iCal calendar and there are also plenty of solutions for iOS that allow you to import Google Calendars. But we are looking for a solution for which we do not need an app, simply because we want to realize direct integration of the two systems. That is possible, at least partly.
There are also apps that allow you to bring the calendars together.
When you log into iCloud and click Calendar, you'll see an icon that resembles a Wi-Fi signal next to your calendar names. By clicking this icon you can share your calendar. Place a check at Public calendar, you will then receive a link that allows others (who know the url) to read the agenda.
The only drawback of this method is that it is a read-only link, ie no new calendar items can be added via this link, but at least it allows you to view the items you have on, for example, your iPhone. add, also show in your Google Calendar. At least, if this method would work out of the box, but it doesn't. If you were to import this link into your Google Calendar, you would get an error message. Fortunately, there is a trick for that too.
You can share your calendar via a button in iCloud.
Share your calendar via iCloud, and copy the link you get to your clipboard. Then surf to //icaltogcal.com/ and paste the link in the field you see. click on Continue, and you will get a new link. Copy this link again to your clipboard and open your Google Calendar. Now click on the arrow next to Other Calendars and select Add via URL. Paste the URL from your clipboard, and voila, the items from your iCal calendar will show up in your Google Calendar.
It's a shame you can't place items in your iCal calendar this way, but at least you have a central place where you can bring all your iCal calendars together.
Convert the link into iCalToGCal, and you can use it in your Google Calendar.