Get notifications on Apple Watch
Active syncing between Google Calendar and the Google Calendar app on iPhone by following this tutorial: https://appletoolbox.com/how-touse-google-calendar-on-apple-watch/. The Calendar app on Apple Watch always syncs with the Calendar app on iPhone so you will now get notifications on Apple Watch.
Even though the Calendar app on iPhone automatically refreshes often, it can take some time for changes in Reclaim till the changes have effect in the Calendar app on iPhone and Apple Watch. To manually refresh immediately:
Navigate to Settings > your_name on the iPhone
Wait a few seconds
Go back to the Calendar app to check that it has refreshed
Get notifications on iPhone
Install Google Calendar app on iPhone
In the Google Calendar app, navigate to Settings > Apps from Google
Under Calendar, choose Google Calendar.
In theory it should not be necessary to install Google Calendar app on iPhone to get notifications if you active syncing between Google Calendar and the Calendar app on iPhone. If you have issues, try installing the Google Calendar app on the iPhone. A benefit of having the Google Calendar app on iPhone is that you can easily add some calendar events without going to the computer or using a browser.
Get notifications on MacBook
Active syncing between Google Calendar and the Calendar app on MacBook by following this video tutorial from 00:00 to 00:59: https://www.youtube.com/watch?v=ZkGzPv6eUvc
In Calendar app on MacBook go to Preferences > Accounts > Google
At the option Refresh Calendars choose Every minute.
We are not aware of any manually way to refresh immediately.