I'm pretty sure all of my Google calendar events show up on my watch, but I forgot to wear it before I left the house, so can't confirm right now. But as long as the calendar is synced on your phone, it should replicate to the watch.
In the Watch app on your phone, there are Settings for Calendar. By default, it's set to mirror the phone's calendar, so if your Google cal is set on your phone it should be on the Watch too, but custom calendar syncing is also possible